1	// SPDX-License-Identifier: GPL-2.0-or-later
2	/*
3	* uvc_video.c -- USB Video Class driver - Video handling
4	*
5	* Copyright (C) 2005-2010
6	* Laurent Pinchart (laurent.pinchart@ideasonboard.com)
7	*/
8
9	#include <linux/dma-mapping.h>
10	#include <linux/highmem.h>
11	#include <linux/kernel.h>
12	#include <linux/list.h>
13	#include <linux/module.h>
14	#include <linux/slab.h>
15	#include <linux/usb.h>
16	#include <linux/usb/hcd.h>
17	#include <linux/videodev2.h>
18	#include <linux/vmalloc.h>
19	#include <linux/wait.h>
20	#include <linux/atomic.h>
21	#include <asm/unaligned.h>
22
23	#include <media/v4l2-common.h>
24
25	#include "uvcvideo.h"
26
27	/* ------------------------------------------------------------------------
28	* UVC Controls
29	*/
30
31	static int __uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
32	u8 intfnum, u8 cs, void *data, u16 size,
33	int timeout)
34	{
35	u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
36	unsigned int pipe;
37
38	pipe = (query & 0x80) ? usb_rcvctrlpipe(dev->udev, 0)
39	: usb_sndctrlpipe(dev->udev, 0);
40	type |= (query & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
41
42	return usb_control_msg(dev: dev->udev, pipe, request: query, requesttype: type, value: cs << 8,
43	index: unit << 8 | intfnum, data, size, timeout);
44	}
45
46	static const char *uvc_query_name(u8 query)
47	{
48	switch (query) {
49	case UVC_SET_CUR:
50	return "SET_CUR";
51	case UVC_GET_CUR:
52	return "GET_CUR";
53	case UVC_GET_MIN:
54	return "GET_MIN";
55	case UVC_GET_MAX:
56	return "GET_MAX";
57	case UVC_GET_RES:
58	return "GET_RES";
59	case UVC_GET_LEN:
60	return "GET_LEN";
61	case UVC_GET_INFO:
62	return "GET_INFO";
63	case UVC_GET_DEF:
64	return "GET_DEF";
65	default:
66	return "<invalid>";
67	}
68	}
69
70	int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
71	u8 intfnum, u8 cs, void *data, u16 size)
72	{
73	int ret;
74	u8 error;
75	u8 tmp;
76
77	ret = __uvc_query_ctrl(dev, query, unit, intfnum, cs, data, size,
78	UVC_CTRL_CONTROL_TIMEOUT);
79	if (likely(ret == size))
80	return 0;
81
82	if (ret != -EPIPE) {
83	dev_err(&dev->udev->dev,
84	"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
85	uvc_query_name(query), cs, unit, ret, size);
86	return ret < 0 ? ret : -EPIPE;
87	}
88
89	/* Reuse data[0] to request the error code. */
90	tmp = *(u8 *)data;
91
92	ret = __uvc_query_ctrl(dev, UVC_GET_CUR, unit: 0, intfnum,
93	UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, size: 1,
94	UVC_CTRL_CONTROL_TIMEOUT);
95
96	error = *(u8 *)data;
97	*(u8 *)data = tmp;
98
99	if (ret != 1)
100	return ret < 0 ? ret : -EPIPE;
101
102	uvc_dbg(dev, CONTROL, "Control error %u\n", error);
103
104	switch (error) {
105	case 0:
106	/* Cannot happen - we received a STALL */
107	return -EPIPE;
108	case 1: /* Not ready */
109	return -EBUSY;
110	case 2: /* Wrong state */
111	return -EACCES;
112	case 3: /* Power */
113	return -EREMOTE;
114	case 4: /* Out of range */
115	return -ERANGE;
116	case 5: /* Invalid unit */
117	case 6: /* Invalid control */
118	case 7: /* Invalid Request */
119	/*
120	* The firmware has not properly implemented
121	* the control or there has been a HW error.
122	*/
123	return -EIO;
124	case 8: /* Invalid value within range */
125	return -EINVAL;
126	default: /* reserved or unknown */
127	break;
128	}
129
130	return -EPIPE;
131	}
132
133	static const struct usb_device_id elgato_cam_link_4k = {
134	USB_DEVICE(0x0fd9, 0x0066)
135	};
136
137	static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
138	struct uvc_streaming_control *ctrl)
139	{
140	const struct uvc_format *format = NULL;
141	const struct uvc_frame *frame = NULL;
142	unsigned int i;
143
144	/*
145	* The response of the Elgato Cam Link 4K is incorrect: The second byte
146	* contains bFormatIndex (instead of being the second byte of bmHint).
147	* The first byte is always zero. The third byte is always 1.
148	*
149	* The UVC 1.5 class specification defines the first five bits in the
150	* bmHint bitfield. The remaining bits are reserved and should be zero.
151	* Therefore a valid bmHint will be less than 32.
152	*
153	* Latest Elgato Cam Link 4K firmware as of 2021-03-23 needs this fix.
154	* MCU: 20.02.19, FPGA: 67
155	*/
156	if (usb_match_one_id(interface: stream->dev->intf, id: &elgato_cam_link_4k) &&
157	ctrl->bmHint > 255) {
158	u8 corrected_format_index = ctrl->bmHint >> 8;
159
160	uvc_dbg(stream->dev, VIDEO,
161	"Correct USB video probe response from {bmHint: 0x%04x, bFormatIndex: %u} to {bmHint: 0x%04x, bFormatIndex: %u}\n",
162	ctrl->bmHint, ctrl->bFormatIndex,
163	1, corrected_format_index);
164	ctrl->bmHint = 1;
165	ctrl->bFormatIndex = corrected_format_index;
166	}
167
168	for (i = 0; i < stream->nformats; ++i) {
169	if (stream->formats[i].index == ctrl->bFormatIndex) {
170	format = &stream->formats[i];
171	break;
172	}
173	}
174
175	if (format == NULL)
176	return;
177
178	for (i = 0; i < format->nframes; ++i) {
179	if (format->frames[i].bFrameIndex == ctrl->bFrameIndex) {
180	frame = &format->frames[i];
181	break;
182	}
183	}
184
185	if (frame == NULL)
186	return;
187
188	if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) ||
189	(ctrl->dwMaxVideoFrameSize == 0 &&
190	stream->dev->uvc_version < 0x0110))
191	ctrl->dwMaxVideoFrameSize =
192	frame->dwMaxVideoFrameBufferSize;
193
194	/*
195	* The "TOSHIBA Web Camera - 5M" Chicony device (04f2:b50b) seems to
196	* compute the bandwidth on 16 bits and erroneously sign-extend it to
197	* 32 bits, resulting in a huge bandwidth value. Detect and fix that
198	* condition by setting the 16 MSBs to 0 when they're all equal to 1.
199	*/
200	if ((ctrl->dwMaxPayloadTransferSize & 0xffff0000) == 0xffff0000)
201	ctrl->dwMaxPayloadTransferSize &= ~0xffff0000;
202
203	if (!(format->flags & UVC_FMT_FLAG_COMPRESSED) &&
204	stream->dev->quirks & UVC_QUIRK_FIX_BANDWIDTH &&
205	stream->intf->num_altsetting > 1) {
206	u32 interval;
207	u32 bandwidth;
208
209	interval = (ctrl->dwFrameInterval > 100000)
210	? ctrl->dwFrameInterval
211	: frame->dwFrameInterval[0];
212
213	/*
214	* Compute a bandwidth estimation by multiplying the frame
215	* size by the number of video frames per second, divide the
216	* result by the number of USB frames (or micro-frames for
217	* high-speed devices) per second and add the UVC header size
218	* (assumed to be 12 bytes long).
219	*/
220	bandwidth = frame->wWidth * frame->wHeight / 8 * format->bpp;
221	bandwidth *= 10000000 / interval + 1;
222	bandwidth /= 1000;
223	if (stream->dev->udev->speed == USB_SPEED_HIGH)
224	bandwidth /= 8;
225	bandwidth += 12;
226
227	/*
228	* The bandwidth estimate is too low for many cameras. Don't use
229	* maximum packet sizes lower than 1024 bytes to try and work
230	* around the problem. According to measurements done on two
231	* different camera models, the value is high enough to get most
232	* resolutions working while not preventing two simultaneous
233	* VGA streams at 15 fps.
234	*/
235	bandwidth = max_t(u32, bandwidth, 1024);
236
237	ctrl->dwMaxPayloadTransferSize = bandwidth;
238	}
239	}
240
241	static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)
242	{
243	/*
244	* Return the size of the video probe and commit controls, which depends
245	* on the protocol version.
246	*/
247	if (stream->dev->uvc_version < 0x0110)
248	return 26;
249	else if (stream->dev->uvc_version < 0x0150)
250	return 34;
251	else
252	return 48;
253	}
254
255	static int uvc_get_video_ctrl(struct uvc_streaming *stream,
256	struct uvc_streaming_control *ctrl, int probe, u8 query)
257	{
258	u16 size = uvc_video_ctrl_size(stream);
259	u8 *data;
260	int ret;
261
262	if ((stream->dev->quirks & UVC_QUIRK_PROBE_DEF) &&
263	query == UVC_GET_DEF)
264	return -EIO;
265
266	data = kmalloc(size, GFP_KERNEL);
267	if (data == NULL)
268	return -ENOMEM;
269
270	ret = __uvc_query_ctrl(dev: stream->dev, query, unit: 0, intfnum: stream->intfnum,
271	cs: probe ? UVC_VS_PROBE_CONTROL : UVC_VS_COMMIT_CONTROL, data,
272	size, timeout: uvc_timeout_param);
273
274	if ((query == UVC_GET_MIN || query == UVC_GET_MAX) && ret == 2) {
275	/*
276	* Some cameras, mostly based on Bison Electronics chipsets,
277	* answer a GET_MIN or GET_MAX request with the wCompQuality
278	* field only.
279	*/
280	uvc_warn_once(stream->dev, UVC_WARN_MINMAX, "UVC non "
281	"compliance - GET_MIN/MAX(PROBE) incorrectly "
282	"supported. Enabling workaround.\n");
283	memset(ctrl, 0, sizeof(*ctrl));
284	ctrl->wCompQuality = le16_to_cpup(p: (__le16 *)data);
285	ret = 0;
286	goto out;
287	} else if (query == UVC_GET_DEF && probe == 1 && ret != size) {
288	/*
289	* Many cameras don't support the GET_DEF request on their
290	* video probe control. Warn once and return, the caller will
291	* fall back to GET_CUR.
292	*/
293	uvc_warn_once(stream->dev, UVC_WARN_PROBE_DEF, "UVC non "
294	"compliance - GET_DEF(PROBE) not supported. "
295	"Enabling workaround.\n");
296	ret = -EIO;
297	goto out;
298	} else if (ret != size) {
299	dev_err(&stream->intf->dev,
300	"Failed to query (%u) UVC %s control : %d (exp. %u).\n",
301	query, probe ? "probe" : "commit", ret, size);
302	ret = (ret == -EPROTO) ? -EPROTO : -EIO;
303	goto out;
304	}
305
306	ctrl->bmHint = le16_to_cpup(p: (__le16 *)&data[0]);
307	ctrl->bFormatIndex = data[2];
308	ctrl->bFrameIndex = data[3];
309	ctrl->dwFrameInterval = le32_to_cpup(p: (__le32 *)&data[4]);
310	ctrl->wKeyFrameRate = le16_to_cpup(p: (__le16 *)&data[8]);
311	ctrl->wPFrameRate = le16_to_cpup(p: (__le16 *)&data[10]);
312	ctrl->wCompQuality = le16_to_cpup(p: (__le16 *)&data[12]);
313	ctrl->wCompWindowSize = le16_to_cpup(p: (__le16 *)&data[14]);
314	ctrl->wDelay = le16_to_cpup(p: (__le16 *)&data[16]);
315	ctrl->dwMaxVideoFrameSize = get_unaligned_le32(p: &data[18]);
316	ctrl->dwMaxPayloadTransferSize = get_unaligned_le32(p: &data[22]);
317
318	if (size >= 34) {
319	ctrl->dwClockFrequency = get_unaligned_le32(p: &data[26]);
320	ctrl->bmFramingInfo = data[30];
321	ctrl->bPreferedVersion = data[31];
322	ctrl->bMinVersion = data[32];
323	ctrl->bMaxVersion = data[33];
324	} else {
325	ctrl->dwClockFrequency = stream->dev->clock_frequency;
326	ctrl->bmFramingInfo = 0;
327	ctrl->bPreferedVersion = 0;
328	ctrl->bMinVersion = 0;
329	ctrl->bMaxVersion = 0;
330	}
331
332	/*
333	* Some broken devices return null or wrong dwMaxVideoFrameSize and
334	* dwMaxPayloadTransferSize fields. Try to get the value from the
335	* format and frame descriptors.
336	*/
337	uvc_fixup_video_ctrl(stream, ctrl);
338	ret = 0;
339
340	out:
341	kfree(objp: data);
342	return ret;
343	}
344
345	static int uvc_set_video_ctrl(struct uvc_streaming *stream,
346	struct uvc_streaming_control *ctrl, int probe)
347	{
348	u16 size = uvc_video_ctrl_size(stream);
349	u8 *data;
350	int ret;
351
352	data = kzalloc(size, GFP_KERNEL);
353	if (data == NULL)
354	return -ENOMEM;
355
356	*(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
357	data[2] = ctrl->bFormatIndex;
358	data[3] = ctrl->bFrameIndex;
359	*(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
360	*(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
361	*(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
362	*(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
363	*(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
364	*(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
365	put_unaligned_le32(val: ctrl->dwMaxVideoFrameSize, p: &data[18]);
366	put_unaligned_le32(val: ctrl->dwMaxPayloadTransferSize, p: &data[22]);
367
368	if (size >= 34) {
369	put_unaligned_le32(val: ctrl->dwClockFrequency, p: &data[26]);
370	data[30] = ctrl->bmFramingInfo;
371	data[31] = ctrl->bPreferedVersion;
372	data[32] = ctrl->bMinVersion;
373	data[33] = ctrl->bMaxVersion;
374	}
375
376	ret = __uvc_query_ctrl(dev: stream->dev, UVC_SET_CUR, unit: 0, intfnum: stream->intfnum,
377	cs: probe ? UVC_VS_PROBE_CONTROL : UVC_VS_COMMIT_CONTROL, data,
378	size, timeout: uvc_timeout_param);
379	if (ret != size) {
380	dev_err(&stream->intf->dev,
381	"Failed to set UVC %s control : %d (exp. %u).\n",
382	probe ? "probe" : "commit", ret, size);
383	ret = -EIO;
384	}
385
386	kfree(objp: data);
387	return ret;
388	}
389
390	int uvc_probe_video(struct uvc_streaming *stream,
391	struct uvc_streaming_control *probe)
392	{
393	struct uvc_streaming_control probe_min, probe_max;
394	unsigned int i;
395	int ret;
396
397	/*
398	* Perform probing. The device should adjust the requested values
399	* according to its capabilities. However, some devices, namely the
400	* first generation UVC Logitech webcams, don't implement the Video
401	* Probe control properly, and just return the needed bandwidth. For
402	* that reason, if the needed bandwidth exceeds the maximum available
403	* bandwidth, try to lower the quality.
404	*/
405	ret = uvc_set_video_ctrl(stream, ctrl: probe, probe: 1);
406	if (ret < 0)
407	goto done;
408
409	/* Get the minimum and maximum values for compression settings. */
410	if (!(stream->dev->quirks & UVC_QUIRK_PROBE_MINMAX)) {
411	ret = uvc_get_video_ctrl(stream, ctrl: &probe_min, probe: 1, UVC_GET_MIN);
412	if (ret < 0)
413	goto done;
414	ret = uvc_get_video_ctrl(stream, ctrl: &probe_max, probe: 1, UVC_GET_MAX);
415	if (ret < 0)
416	goto done;
417
418	probe->wCompQuality = probe_max.wCompQuality;
419	}
420
421	for (i = 0; i < 2; ++i) {
422	ret = uvc_set_video_ctrl(stream, ctrl: probe, probe: 1);
423	if (ret < 0)
424	goto done;
425	ret = uvc_get_video_ctrl(stream, ctrl: probe, probe: 1, UVC_GET_CUR);
426	if (ret < 0)
427	goto done;
428
429	if (stream->intf->num_altsetting == 1)
430	break;
431
432	if (probe->dwMaxPayloadTransferSize <= stream->maxpsize)
433	break;
434
435	if (stream->dev->quirks & UVC_QUIRK_PROBE_MINMAX) {
436	ret = -ENOSPC;
437	goto done;
438	}
439
440	/* TODO: negotiate compression parameters */
441	probe->wKeyFrameRate = probe_min.wKeyFrameRate;
442	probe->wPFrameRate = probe_min.wPFrameRate;
443	probe->wCompQuality = probe_max.wCompQuality;
444	probe->wCompWindowSize = probe_min.wCompWindowSize;
445	}
446
447	done:
448	return ret;
449	}
450
451	static int uvc_commit_video(struct uvc_streaming *stream,
452	struct uvc_streaming_control *probe)
453	{
454	return uvc_set_video_ctrl(stream, ctrl: probe, probe: 0);
455	}
456
457	/* -----------------------------------------------------------------------------
458	* Clocks and timestamps
459	*/
460
461	static inline ktime_t uvc_video_get_time(void)
462	{
463	if (uvc_clock_param == CLOCK_MONOTONIC)
464	return ktime_get();
465	else
466	return ktime_get_real();
467	}
468
469	static void
470	uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
471	const u8 *data, int len)
472	{
473	struct uvc_clock_sample *sample;
474	unsigned int header_size;
475	bool has_pts = false;
476	bool has_scr = false;
477	unsigned long flags;
478	ktime_t time;
479	u16 host_sof;
480	u16 dev_sof;
481
482	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
483	case UVC_STREAM_PTS | UVC_STREAM_SCR:
484	header_size = 12;
485	has_pts = true;
486	has_scr = true;
487	break;
488	case UVC_STREAM_PTS:
489	header_size = 6;
490	has_pts = true;
491	break;
492	case UVC_STREAM_SCR:
493	header_size = 8;
494	has_scr = true;
495	break;
496	default:
497	header_size = 2;
498	break;
499	}
500
501	/* Check for invalid headers. */
502	if (len < header_size)
503	return;
504
505	/*
506	* Extract the timestamps:
507	*
508	* - store the frame PTS in the buffer structure
509	* - if the SCR field is present, retrieve the host SOF counter and
510	* kernel timestamps and store them with the SCR STC and SOF fields
511	* in the ring buffer
512	*/
513	if (has_pts && buf != NULL)
514	buf->pts = get_unaligned_le32(p: &data[2]);
515
516	if (!has_scr)
517	return;
518
519	/*
520	* To limit the amount of data, drop SCRs with an SOF identical to the
521	* previous one. This filtering is also needed to support UVC 1.5, where
522	* all the data packets of the same frame contains the same SOF. In that
523	* case only the first one will match the host_sof.
524	*/
525	dev_sof = get_unaligned_le16(p: &data[header_size - 2]);
526	if (dev_sof == stream->clock.last_sof)
527	return;
528
529	stream->clock.last_sof = dev_sof;
530
531	host_sof = usb_get_current_frame_number(usb_dev: stream->dev->udev);
532	time = uvc_video_get_time();
533
534	/*
535	* The UVC specification allows device implementations that can't obtain
536	* the USB frame number to keep their own frame counters as long as they
537	* match the size and frequency of the frame number associated with USB
538	* SOF tokens. The SOF values sent by such devices differ from the USB
539	* SOF tokens by a fixed offset that needs to be estimated and accounted
540	* for to make timestamp recovery as accurate as possible.
541	*
542	* The offset is estimated the first time a device SOF value is received
543	* as the difference between the host and device SOF values. As the two
544	* SOF values can differ slightly due to transmission delays, consider
545	* that the offset is null if the difference is not higher than 10 ms
546	* (negative differences can not happen and are thus considered as an
547	* offset). The video commit control wDelay field should be used to
548	* compute a dynamic threshold instead of using a fixed 10 ms value, but
549	* devices don't report reliable wDelay values.
550	*
551	* See uvc_video_clock_host_sof() for an explanation regarding why only
552	* the 8 LSBs of the delta are kept.
553	*/
554	if (stream->clock.sof_offset == (u16)-1) {
555	u16 delta_sof = (host_sof - dev_sof) & 255;
556	if (delta_sof >= 10)
557	stream->clock.sof_offset = delta_sof;
558	else
559	stream->clock.sof_offset = 0;
560	}
561
562	dev_sof = (dev_sof + stream->clock.sof_offset) & 2047;
563
564	spin_lock_irqsave(&stream->clock.lock, flags);
565
566	sample = &stream->clock.samples[stream->clock.head];
567	sample->dev_stc = get_unaligned_le32(p: &data[header_size - 6]);
568	sample->dev_sof = dev_sof;
569	sample->host_sof = host_sof;
570	sample->host_time = time;
571
572	/* Update the sliding window head and count. */
573	stream->clock.head = (stream->clock.head + 1) % stream->clock.size;
574
575	if (stream->clock.count < stream->clock.size)
576	stream->clock.count++;
577
578	spin_unlock_irqrestore(lock: &stream->clock.lock, flags);
579	}
580
581	static void uvc_video_clock_reset(struct uvc_streaming *stream)
582	{
583	struct uvc_clock *clock = &stream->clock;
584
585	clock->head = 0;
586	clock->count = 0;
587	clock->last_sof = -1;
588	clock->sof_offset = -1;
589	}
590
591	static int uvc_video_clock_init(struct uvc_streaming *stream)
592	{
593	struct uvc_clock *clock = &stream->clock;
594
595	spin_lock_init(&clock->lock);
596	clock->size = 32;
597
598	clock->samples = kmalloc_array(n: clock->size, size: sizeof(*clock->samples),
599	GFP_KERNEL);
600	if (clock->samples == NULL)
601	return -ENOMEM;
602
603	uvc_video_clock_reset(stream);
604
605	return 0;
606	}
607
608	static void uvc_video_clock_cleanup(struct uvc_streaming *stream)
609	{
610	kfree(objp: stream->clock.samples);
611	stream->clock.samples = NULL;
612	}
613
614	/*
615	* uvc_video_clock_host_sof - Return the host SOF value for a clock sample
616	*
617	* Host SOF counters reported by usb_get_current_frame_number() usually don't
618	* cover the whole 11-bits SOF range (0-2047) but are limited to the HCI frame
619	* schedule window. They can be limited to 8, 9 or 10 bits depending on the host
620	* controller and its configuration.
621	*
622	* We thus need to recover the SOF value corresponding to the host frame number.
623	* As the device and host frame numbers are sampled in a short interval, the
624	* difference between their values should be equal to a small delta plus an
625	* integer multiple of 256 caused by the host frame number limited precision.
626	*
627	* To obtain the recovered host SOF value, compute the small delta by masking
628	* the high bits of the host frame counter and device SOF difference and add it
629	* to the device SOF value.
630	*/
631	static u16 uvc_video_clock_host_sof(const struct uvc_clock_sample *sample)
632	{
633	/* The delta value can be negative. */
634	s8 delta_sof;
635
636	delta_sof = (sample->host_sof - sample->dev_sof) & 255;
637
638	return (sample->dev_sof + delta_sof) & 2047;
639	}
640
641	/*
642	* uvc_video_clock_update - Update the buffer timestamp
643	*
644	* This function converts the buffer PTS timestamp to the host clock domain by
645	* going through the USB SOF clock domain and stores the result in the V4L2
646	* buffer timestamp field.
647	*
648	* The relationship between the device clock and the host clock isn't known.
649	* However, the device and the host share the common USB SOF clock which can be
650	* used to recover that relationship.
651	*
652	* The relationship between the device clock and the USB SOF clock is considered
653	* to be linear over the clock samples sliding window and is given by
654	*
655	* SOF = m * PTS + p
656	*
657	* Several methods to compute the slope (m) and intercept (p) can be used. As
658	* the clock drift should be small compared to the sliding window size, we
659	* assume that the line that goes through the points at both ends of the window
660	* is a good approximation. Naming those points P1 and P2, we get
661	*
662	* SOF = (SOF2 - SOF1) / (STC2 - STC1) * PTS
663	* + (SOF1 * STC2 - SOF2 * STC1) / (STC2 - STC1)
664	*
665	* or
666	*
667	* SOF = ((SOF2 - SOF1) * PTS + SOF1 * STC2 - SOF2 * STC1) / (STC2 - STC1) (1)
668	*
669	* to avoid losing precision in the division. Similarly, the host timestamp is
670	* computed with
671	*
672	* TS = ((TS2 - TS1) * SOF + TS1 * SOF2 - TS2 * SOF1) / (SOF2 - SOF1) (2)
673	*
674	* SOF values are coded on 11 bits by USB. We extend their precision with 16
675	* decimal bits, leading to a 11.16 coding.
676	*
677	* TODO: To avoid surprises with device clock values, PTS/STC timestamps should
678	* be normalized using the nominal device clock frequency reported through the
679	* UVC descriptors.
680	*
681	* Both the PTS/STC and SOF counters roll over, after a fixed but device
682	* specific amount of time for PTS/STC and after 2048ms for SOF. As long as the
683	* sliding window size is smaller than the rollover period, differences computed
684	* on unsigned integers will produce the correct result. However, the p term in
685	* the linear relations will be miscomputed.
686	*
687	* To fix the issue, we subtract a constant from the PTS and STC values to bring
688	* PTS to half the 32 bit STC range. The sliding window STC values then fit into
689	* the 32 bit range without any rollover.
690	*
691	* Similarly, we add 2048 to the device SOF values to make sure that the SOF
692	* computed by (1) will never be smaller than 0. This offset is then compensated
693	* by adding 2048 to the SOF values used in (2). However, this doesn't prevent
694	* rollovers between (1) and (2): the SOF value computed by (1) can be slightly
695	* lower than 4096, and the host SOF counters can have rolled over to 2048. This
696	* case is handled by subtracting 2048 from the SOF value if it exceeds the host
697	* SOF value at the end of the sliding window.
698	*
699	* Finally we subtract a constant from the host timestamps to bring the first
700	* timestamp of the sliding window to 1s.
701	*/
702	void uvc_video_clock_update(struct uvc_streaming *stream,
703	struct vb2_v4l2_buffer *vbuf,
704	struct uvc_buffer *buf)
705	{
706	struct uvc_clock *clock = &stream->clock;
707	struct uvc_clock_sample *first;
708	struct uvc_clock_sample *last;
709	unsigned long flags;
710	u64 timestamp;
711	u32 delta_stc;
712	u32 y1, y2;
713	u32 x1, x2;
714	u32 mean;
715	u32 sof;
716	u64 y;
717
718	if (!uvc_hw_timestamps_param)
719	return;
720
721	/*
722	* We will get called from __vb2_queue_cancel() if there are buffers
723	* done but not dequeued by the user, but the sample array has already
724	* been released at that time. Just bail out in that case.
725	*/
726	if (!clock->samples)
727	return;
728
729	spin_lock_irqsave(&clock->lock, flags);
730
731	if (clock->count < clock->size)
732	goto done;
733
734	first = &clock->samples[clock->head];
735	last = &clock->samples[(clock->head - 1) % clock->size];
736
737	/* First step, PTS to SOF conversion. */
738	delta_stc = buf->pts - (1UL << 31);
739	x1 = first->dev_stc - delta_stc;
740	x2 = last->dev_stc - delta_stc;
741	if (x1 == x2)
742	goto done;
743
744	y1 = (first->dev_sof + 2048) << 16;
745	y2 = (last->dev_sof + 2048) << 16;
746	if (y2 < y1)
747	y2 += 2048 << 16;
748
749	y = (u64)(y2 - y1) * (1ULL << 31) + (u64)y1 * (u64)x2
750	- (u64)y2 * (u64)x1;
751	y = div_u64(dividend: y, divisor: x2 - x1);
752
753	sof = y;
754
755	uvc_dbg(stream->dev, CLOCK,
756	"%s: PTS %u y %llu.%06llu SOF %u.%06llu (x1 %u x2 %u y1 %u y2 %u SOF offset %u)\n",
757	stream->dev->name, buf->pts,
758	y >> 16, div_u64((y & 0xffff) * 1000000, 65536),
759	sof >> 16, div_u64(((u64)sof & 0xffff) * 1000000LLU, 65536),
760	x1, x2, y1, y2, clock->sof_offset);
761
762	/* Second step, SOF to host clock conversion. */
763	x1 = (uvc_video_clock_host_sof(sample: first) + 2048) << 16;
764	x2 = (uvc_video_clock_host_sof(sample: last) + 2048) << 16;
765	if (x2 < x1)
766	x2 += 2048 << 16;
767	if (x1 == x2)
768	goto done;
769
770	y1 = NSEC_PER_SEC;
771	y2 = (u32)ktime_to_ns(ktime_sub(last->host_time, first->host_time)) + y1;
772
773	/*
774	* Interpolated and host SOF timestamps can wrap around at slightly
775	* different times. Handle this by adding or removing 2048 to or from
776	* the computed SOF value to keep it close to the SOF samples mean
777	* value.
778	*/
779	mean = (x1 + x2) / 2;
780	if (mean - (1024 << 16) > sof)
781	sof += 2048 << 16;
782	else if (sof > mean + (1024 << 16))
783	sof -= 2048 << 16;
784
785	y = (u64)(y2 - y1) * (u64)sof + (u64)y1 * (u64)x2
786	- (u64)y2 * (u64)x1;
787	y = div_u64(dividend: y, divisor: x2 - x1);
788
789	timestamp = ktime_to_ns(kt: first->host_time) + y - y1;
790
791	uvc_dbg(stream->dev, CLOCK,
792	"%s: SOF %u.%06llu y %llu ts %llu buf ts %llu (x1 %u/%u/%u x2 %u/%u/%u y1 %u y2 %u)\n",
793	stream->dev->name,
794	sof >> 16, div_u64(((u64)sof & 0xffff) * 1000000LLU, 65536),
795	y, timestamp, vbuf->vb2_buf.timestamp,
796	x1, first->host_sof, first->dev_sof,
797	x2, last->host_sof, last->dev_sof, y1, y2);
798
799	/* Update the V4L2 buffer. */
800	vbuf->vb2_buf.timestamp = timestamp;
801
802	done:
803	spin_unlock_irqrestore(lock: &clock->lock, flags);
804	}
805
806	/* ------------------------------------------------------------------------
807	* Stream statistics
808	*/
809
810	static void uvc_video_stats_decode(struct uvc_streaming *stream,
811	const u8 *data, int len)
812	{
813	unsigned int header_size;
814	bool has_pts = false;
815	bool has_scr = false;
816	u16 scr_sof;
817	u32 scr_stc;
818	u32 pts;
819
820	if (stream->stats.stream.nb_frames == 0 &&
821	stream->stats.frame.nb_packets == 0)
822	stream->stats.stream.start_ts = ktime_get();
823
824	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
825	case UVC_STREAM_PTS | UVC_STREAM_SCR:
826	header_size = 12;
827	has_pts = true;
828	has_scr = true;
829	break;
830	case UVC_STREAM_PTS:
831	header_size = 6;
832	has_pts = true;
833	break;
834	case UVC_STREAM_SCR:
835	header_size = 8;
836	has_scr = true;
837	break;
838	default:
839	header_size = 2;
840	break;
841	}
842
843	/* Check for invalid headers. */
844	if (len < header_size || data[0] < header_size) {
845	stream->stats.frame.nb_invalid++;
846	return;
847	}
848
849	/* Extract the timestamps. */
850	if (has_pts)
851	pts = get_unaligned_le32(p: &data[2]);
852
853	if (has_scr) {
854	scr_stc = get_unaligned_le32(p: &data[header_size - 6]);
855	scr_sof = get_unaligned_le16(p: &data[header_size - 2]);
856	}
857
858	/* Is PTS constant through the whole frame ? */
859	if (has_pts && stream->stats.frame.nb_pts) {
860	if (stream->stats.frame.pts != pts) {
861	stream->stats.frame.nb_pts_diffs++;
862	stream->stats.frame.last_pts_diff =
863	stream->stats.frame.nb_packets;
864	}
865	}
866
867	if (has_pts) {
868	stream->stats.frame.nb_pts++;
869	stream->stats.frame.pts = pts;
870	}
871
872	/*
873	* Do all frames have a PTS in their first non-empty packet, or before
874	* their first empty packet ?
875	*/
876	if (stream->stats.frame.size == 0) {
877	if (len > header_size)
878	stream->stats.frame.has_initial_pts = has_pts;
879	if (len == header_size && has_pts)
880	stream->stats.frame.has_early_pts = true;
881	}
882
883	/* Do the SCR.STC and SCR.SOF fields vary through the frame ? */
884	if (has_scr && stream->stats.frame.nb_scr) {
885	if (stream->stats.frame.scr_stc != scr_stc)
886	stream->stats.frame.nb_scr_diffs++;
887	}
888
889	if (has_scr) {
890	/* Expand the SOF counter to 32 bits and store its value. */
891	if (stream->stats.stream.nb_frames > 0 ||
892	stream->stats.frame.nb_scr > 0)
893	stream->stats.stream.scr_sof_count +=
894	(scr_sof - stream->stats.stream.scr_sof) % 2048;
895	stream->stats.stream.scr_sof = scr_sof;
896
897	stream->stats.frame.nb_scr++;
898	stream->stats.frame.scr_stc = scr_stc;
899	stream->stats.frame.scr_sof = scr_sof;
900
901	if (scr_sof < stream->stats.stream.min_sof)
902	stream->stats.stream.min_sof = scr_sof;
903	if (scr_sof > stream->stats.stream.max_sof)
904	stream->stats.stream.max_sof = scr_sof;
905	}
906
907	/* Record the first non-empty packet number. */
908	if (stream->stats.frame.size == 0 && len > header_size)
909	stream->stats.frame.first_data = stream->stats.frame.nb_packets;
910
911	/* Update the frame size. */
912	stream->stats.frame.size += len - header_size;
913
914	/* Update the packets counters. */
915	stream->stats.frame.nb_packets++;
916	if (len <= header_size)
917	stream->stats.frame.nb_empty++;
918
919	if (data[1] & UVC_STREAM_ERR)
920	stream->stats.frame.nb_errors++;
921	}
922
923	static void uvc_video_stats_update(struct uvc_streaming *stream)
924	{
925	struct uvc_stats_frame *frame = &stream->stats.frame;
926
927	uvc_dbg(stream->dev, STATS,
928	"frame %u stats: %u/%u/%u packets, %u/%u/%u pts (%searly %sinitial), %u/%u scr, last pts/stc/sof %u/%u/%u\n",
929	stream->sequence, frame->first_data,
930	frame->nb_packets - frame->nb_empty, frame->nb_packets,
931	frame->nb_pts_diffs, frame->last_pts_diff, frame->nb_pts,
932	frame->has_early_pts ? "" : "!",
933	frame->has_initial_pts ? "" : "!",
934	frame->nb_scr_diffs, frame->nb_scr,
935	frame->pts, frame->scr_stc, frame->scr_sof);
936
937	stream->stats.stream.nb_frames++;
938	stream->stats.stream.nb_packets += stream->stats.frame.nb_packets;
939	stream->stats.stream.nb_empty += stream->stats.frame.nb_empty;
940	stream->stats.stream.nb_errors += stream->stats.frame.nb_errors;
941	stream->stats.stream.nb_invalid += stream->stats.frame.nb_invalid;
942
943	if (frame->has_early_pts)
944	stream->stats.stream.nb_pts_early++;
945	if (frame->has_initial_pts)
946	stream->stats.stream.nb_pts_initial++;
947	if (frame->last_pts_diff <= frame->first_data)
948	stream->stats.stream.nb_pts_constant++;
949	if (frame->nb_scr >= frame->nb_packets - frame->nb_empty)
950	stream->stats.stream.nb_scr_count_ok++;
951	if (frame->nb_scr_diffs + 1 == frame->nb_scr)
952	stream->stats.stream.nb_scr_diffs_ok++;
953
954	memset(&stream->stats.frame, 0, sizeof(stream->stats.frame));
955	}
956
957	size_t uvc_video_stats_dump(struct uvc_streaming *stream, char *buf,
958	size_t size)
959	{
960	unsigned int scr_sof_freq;
961	unsigned int duration;
962	size_t count = 0;
963
964	/*
965	* Compute the SCR.SOF frequency estimate. At the nominal 1kHz SOF
966	* frequency this will not overflow before more than 1h.
967	*/
968	duration = ktime_ms_delta(later: stream->stats.stream.stop_ts,
969	earlier: stream->stats.stream.start_ts);
970	if (duration != 0)
971	scr_sof_freq = stream->stats.stream.scr_sof_count * 1000
972	/ duration;
973	else
974	scr_sof_freq = 0;
975
976	count += scnprintf(buf: buf + count, size: size - count,
977	fmt: "frames: %u\npackets: %u\nempty: %u\n"
978	"errors: %u\ninvalid: %u\n",
979	stream->stats.stream.nb_frames,
980	stream->stats.stream.nb_packets,
981	stream->stats.stream.nb_empty,
982	stream->stats.stream.nb_errors,
983	stream->stats.stream.nb_invalid);
984	count += scnprintf(buf: buf + count, size: size - count,
985	fmt: "pts: %u early, %u initial, %u ok\n",
986	stream->stats.stream.nb_pts_early,
987	stream->stats.stream.nb_pts_initial,
988	stream->stats.stream.nb_pts_constant);
989	count += scnprintf(buf: buf + count, size: size - count,
990	fmt: "scr: %u count ok, %u diff ok\n",
991	stream->stats.stream.nb_scr_count_ok,
992	stream->stats.stream.nb_scr_diffs_ok);
993	count += scnprintf(buf: buf + count, size: size - count,
994	fmt: "sof: %u <= sof <= %u, freq %u.%03u kHz\n",
995	stream->stats.stream.min_sof,
996	stream->stats.stream.max_sof,
997	scr_sof_freq / 1000, scr_sof_freq % 1000);
998
999	return count;
1000	}
1001
1002	static void uvc_video_stats_start(struct uvc_streaming *stream)
1003	{
1004	memset(&stream->stats, 0, sizeof(stream->stats));
1005	stream->stats.stream.min_sof = 2048;
1006	}
1007
1008	static void uvc_video_stats_stop(struct uvc_streaming *stream)
1009	{
1010	stream->stats.stream.stop_ts = ktime_get();
1011	}
1012
1013	/* ------------------------------------------------------------------------
1014	* Video codecs
1015	*/
1016
1017	/*
1018	* Video payload decoding is handled by uvc_video_decode_start(),
1019	* uvc_video_decode_data() and uvc_video_decode_end().
1020	*
1021	* uvc_video_decode_start is called with URB data at the start of a bulk or
1022	* isochronous payload. It processes header data and returns the header size
1023	* in bytes if successful. If an error occurs, it returns a negative error
1024	* code. The following error codes have special meanings.
1025	*
1026	* - EAGAIN informs the caller that the current video buffer should be marked
1027	* as done, and that the function should be called again with the same data
1028	* and a new video buffer. This is used when end of frame conditions can be
1029	* reliably detected at the beginning of the next frame only.
1030	*
1031	* If an error other than -EAGAIN is returned, the caller will drop the current
1032	* payload. No call to uvc_video_decode_data and uvc_video_decode_end will be
1033	* made until the next payload. -ENODATA can be used to drop the current
1034	* payload if no other error code is appropriate.
1035	*
1036	* uvc_video_decode_data is called for every URB with URB data. It copies the
1037	* data to the video buffer.
1038	*
1039	* uvc_video_decode_end is called with header data at the end of a bulk or
1040	* isochronous payload. It performs any additional header data processing and
1041	* returns 0 or a negative error code if an error occurred. As header data have
1042	* already been processed by uvc_video_decode_start, this functions isn't
1043	* required to perform sanity checks a second time.
1044	*
1045	* For isochronous transfers where a payload is always transferred in a single
1046	* URB, the three functions will be called in a row.
1047	*
1048	* To let the decoder process header data and update its internal state even
1049	* when no video buffer is available, uvc_video_decode_start must be prepared
1050	* to be called with a NULL buf parameter. uvc_video_decode_data and
1051	* uvc_video_decode_end will never be called with a NULL buffer.
1052	*/
1053	static int uvc_video_decode_start(struct uvc_streaming *stream,
1054	struct uvc_buffer *buf, const u8 *data, int len)
1055	{
1056	u8 fid;
1057
1058	/*
1059	* Sanity checks:
1060	* - packet must be at least 2 bytes long
1061	* - bHeaderLength value must be at least 2 bytes (see above)
1062	* - bHeaderLength value can't be larger than the packet size.
1063	*/
1064	if (len < 2 || data[0] < 2 || data[0] > len) {
1065	stream->stats.frame.nb_invalid++;
1066	return -EINVAL;
1067	}
1068
1069	fid = data[1] & UVC_STREAM_FID;
1070
1071	/*
1072	* Increase the sequence number regardless of any buffer states, so
1073	* that discontinuous sequence numbers always indicate lost frames.
1074	*/
1075	if (stream->last_fid != fid) {
1076	stream->sequence++;
1077	if (stream->sequence)
1078	uvc_video_stats_update(stream);
1079	}
1080
1081	uvc_video_clock_decode(stream, buf, data, len);
1082	uvc_video_stats_decode(stream, data, len);
1083
1084	/*
1085	* Store the payload FID bit and return immediately when the buffer is
1086	* NULL.
1087	*/
1088	if (buf == NULL) {
1089	stream->last_fid = fid;
1090	return -ENODATA;
1091	}
1092
1093	/* Mark the buffer as bad if the error bit is set. */
1094	if (data[1] & UVC_STREAM_ERR) {
1095	uvc_dbg(stream->dev, FRAME,
1096	"Marking buffer as bad (error bit set)\n");
1097	buf->error = 1;
1098	}
1099
1100	/*
1101	* Synchronize to the input stream by waiting for the FID bit to be
1102	* toggled when the buffer state is not UVC_BUF_STATE_ACTIVE.
1103	* stream->last_fid is initialized to -1, so the first isochronous
1104	* frame will always be in sync.
1105	*
1106	* If the device doesn't toggle the FID bit, invert stream->last_fid
1107	* when the EOF bit is set to force synchronisation on the next packet.
1108	*/
1109	if (buf->state != UVC_BUF_STATE_ACTIVE) {
1110	if (fid == stream->last_fid) {
1111	uvc_dbg(stream->dev, FRAME,
1112	"Dropping payload (out of sync)\n");
1113	if ((stream->dev->quirks & UVC_QUIRK_STREAM_NO_FID) &&
1114	(data[1] & UVC_STREAM_EOF))
1115	stream->last_fid ^= UVC_STREAM_FID;
1116	return -ENODATA;
1117	}
1118
1119	buf->buf.field = V4L2_FIELD_NONE;
1120	buf->buf.sequence = stream->sequence;
1121	buf->buf.vb2_buf.timestamp = ktime_to_ns(kt: uvc_video_get_time());
1122
1123	/* TODO: Handle PTS and SCR. */
1124	buf->state = UVC_BUF_STATE_ACTIVE;
1125	}
1126
1127	/*
1128	* Mark the buffer as done if we're at the beginning of a new frame.
1129	* End of frame detection is better implemented by checking the EOF
1130	* bit (FID bit toggling is delayed by one frame compared to the EOF
1131	* bit), but some devices don't set the bit at end of frame (and the
1132	* last payload can be lost anyway). We thus must check if the FID has
1133	* been toggled.
1134	*
1135	* stream->last_fid is initialized to -1, so the first isochronous
1136	* frame will never trigger an end of frame detection.
1137	*
1138	* Empty buffers (bytesused == 0) don't trigger end of frame detection
1139	* as it doesn't make sense to return an empty buffer. This also
1140	* avoids detecting end of frame conditions at FID toggling if the
1141	* previous payload had the EOF bit set.
1142	*/
1143	if (fid != stream->last_fid && buf->bytesused != 0) {
1144	uvc_dbg(stream->dev, FRAME,
1145	"Frame complete (FID bit toggled)\n");
1146	buf->state = UVC_BUF_STATE_READY;
1147	return -EAGAIN;
1148	}
1149
1150	stream->last_fid = fid;
1151
1152	return data[0];
1153	}
1154
1155	static inline enum dma_data_direction uvc_stream_dir(
1156	struct uvc_streaming *stream)
1157	{
1158	if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
1159	return DMA_FROM_DEVICE;
1160	else
1161	return DMA_TO_DEVICE;
1162	}
1163
1164	static inline struct device *uvc_stream_to_dmadev(struct uvc_streaming *stream)
1165	{
1166	return bus_to_hcd(bus: stream->dev->udev->bus)->self.sysdev;
1167	}
1168
1169	static int uvc_submit_urb(struct uvc_urb *uvc_urb, gfp_t mem_flags)
1170	{
1171	/* Sync DMA. */
1172	dma_sync_sgtable_for_device(dev: uvc_stream_to_dmadev(stream: uvc_urb->stream),
1173	sgt: uvc_urb->sgt,
1174	dir: uvc_stream_dir(stream: uvc_urb->stream));
1175	return usb_submit_urb(urb: uvc_urb->urb, mem_flags);
1176	}
1177
1178	/*
1179	* uvc_video_decode_data_work: Asynchronous memcpy processing
1180	*
1181	* Copy URB data to video buffers in process context, releasing buffer
1182	* references and requeuing the URB when done.
1183	*/
1184	static void uvc_video_copy_data_work(struct work_struct *work)
1185	{
1186	struct uvc_urb *uvc_urb = container_of(work, struct uvc_urb, work);
1187	unsigned int i;
1188	int ret;
1189
1190	for (i = 0; i < uvc_urb->async_operations; i++) {
1191	struct uvc_copy_op *op = &uvc_urb->copy_operations[i];
1192
1193	memcpy(op->dst, op->src, op->len);
1194
1195	/* Release reference taken on this buffer. */
1196	uvc_queue_buffer_release(buf: op->buf);
1197	}
1198
1199	ret = uvc_submit_urb(uvc_urb, GFP_KERNEL);
1200	if (ret < 0)
1201	dev_err(&uvc_urb->stream->intf->dev,
1202	"Failed to resubmit video URB (%d).\n", ret);
1203	}
1204
1205	static void uvc_video_decode_data(struct uvc_urb *uvc_urb,
1206	struct uvc_buffer *buf, const u8 *data, int len)
1207	{
1208	unsigned int active_op = uvc_urb->async_operations;
1209	struct uvc_copy_op *op = &uvc_urb->copy_operations[active_op];
1210	unsigned int maxlen;
1211
1212	if (len <= 0)
1213	return;
1214
1215	maxlen = buf->length - buf->bytesused;
1216
1217	/* Take a buffer reference for async work. */
1218	kref_get(kref: &buf->ref);
1219
1220	op->buf = buf;
1221	op->src = data;
1222	op->dst = buf->mem + buf->bytesused;
1223	op->len = min_t(unsigned int, len, maxlen);
1224
1225	buf->bytesused += op->len;
1226
1227	/* Complete the current frame if the buffer size was exceeded. */
1228	if (len > maxlen) {
1229	uvc_dbg(uvc_urb->stream->dev, FRAME,
1230	"Frame complete (overflow)\n");
1231	buf->error = 1;
1232	buf->state = UVC_BUF_STATE_READY;
1233	}
1234
1235	uvc_urb->async_operations++;
1236	}
1237
1238	static void uvc_video_decode_end(struct uvc_streaming *stream,
1239	struct uvc_buffer *buf, const u8 *data, int len)
1240	{
1241	/* Mark the buffer as done if the EOF marker is set. */
1242	if (data[1] & UVC_STREAM_EOF && buf->bytesused != 0) {
1243	uvc_dbg(stream->dev, FRAME, "Frame complete (EOF found)\n");
1244	if (data[0] == len)
1245	uvc_dbg(stream->dev, FRAME, "EOF in empty payload\n");
1246	buf->state = UVC_BUF_STATE_READY;
1247	if (stream->dev->quirks & UVC_QUIRK_STREAM_NO_FID)
1248	stream->last_fid ^= UVC_STREAM_FID;
1249	}
1250	}
1251
1252	/*
1253	* Video payload encoding is handled by uvc_video_encode_header() and
1254	* uvc_video_encode_data(). Only bulk transfers are currently supported.
1255	*
1256	* uvc_video_encode_header is called at the start of a payload. It adds header
1257	* data to the transfer buffer and returns the header size. As the only known
1258	* UVC output device transfers a whole frame in a single payload, the EOF bit
1259	* is always set in the header.
1260	*
1261	* uvc_video_encode_data is called for every URB and copies the data from the
1262	* video buffer to the transfer buffer.
1263	*/
1264	static int uvc_video_encode_header(struct uvc_streaming *stream,
1265	struct uvc_buffer *buf, u8 *data, int len)
1266	{
1267	data[0] = 2; /* Header length */
1268	data[1] = UVC_STREAM_EOH | UVC_STREAM_EOF
1269	| (stream->last_fid & UVC_STREAM_FID);
1270	return 2;
1271	}
1272
1273	static int uvc_video_encode_data(struct uvc_streaming *stream,
1274	struct uvc_buffer *buf, u8 *data, int len)
1275	{
1276	struct uvc_video_queue *queue = &stream->queue;
1277	unsigned int nbytes;
1278	void *mem;
1279
1280	/* Copy video data to the URB buffer. */
1281	mem = buf->mem + queue->buf_used;
1282	nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
1283	nbytes = min(stream->bulk.max_payload_size - stream->bulk.payload_size,
1284	nbytes);
1285	memcpy(data, mem, nbytes);
1286
1287	queue->buf_used += nbytes;
1288
1289	return nbytes;
1290	}
1291
1292	/* ------------------------------------------------------------------------
1293	* Metadata
1294	*/
1295
1296	/*
1297	* Additionally to the payload headers we also want to provide the user with USB
1298	* Frame Numbers and system time values. The resulting buffer is thus composed
1299	* of blocks, containing a 64-bit timestamp in nanoseconds, a 16-bit USB Frame
1300	* Number, and a copy of the payload header.
1301	*
1302	* Ideally we want to capture all payload headers for each frame. However, their
1303	* number is unknown and unbound. We thus drop headers that contain no vendor
1304	* data and that either contain no SCR value or an SCR value identical to the
1305	* previous header.
1306	*/
1307	static void uvc_video_decode_meta(struct uvc_streaming *stream,
1308	struct uvc_buffer *meta_buf,
1309	const u8 *mem, unsigned int length)
1310	{
1311	struct uvc_meta_buf *meta;
1312	size_t len_std = 2;
1313	bool has_pts, has_scr;
1314	unsigned long flags;
1315	unsigned int sof;
1316	ktime_t time;
1317	const u8 *scr;
1318
1319	if (!meta_buf || length == 2)
1320	return;
1321
1322	if (meta_buf->length - meta_buf->bytesused <
1323	length + sizeof(meta->ns) + sizeof(meta->sof)) {
1324	meta_buf->error = 1;
1325	return;
1326	}
1327
1328	has_pts = mem[1] & UVC_STREAM_PTS;
1329	has_scr = mem[1] & UVC_STREAM_SCR;
1330
1331	if (has_pts) {
1332	len_std += 4;
1333	scr = mem + 6;
1334	} else {
1335	scr = mem + 2;
1336	}
1337
1338	if (has_scr)
1339	len_std += 6;
1340
1341	if (stream->meta.format == V4L2_META_FMT_UVC)
1342	length = len_std;
1343
1344	if (length == len_std && (!has_scr ||
1345	!memcmp(p: scr, q: stream->clock.last_scr, size: 6)))
1346	return;
1347
1348	meta = (struct uvc_meta_buf *)((u8 *)meta_buf->mem + meta_buf->bytesused);
1349	local_irq_save(flags);
1350	time = uvc_video_get_time();
1351	sof = usb_get_current_frame_number(usb_dev: stream->dev->udev);
1352	local_irq_restore(flags);
1353	put_unaligned(ktime_to_ns(time), &meta->ns);
1354	put_unaligned(sof, &meta->sof);
1355
1356	if (has_scr)
1357	memcpy(stream->clock.last_scr, scr, 6);
1358
1359	meta->length = mem[0];
1360	meta->flags = mem[1];
1361	memcpy(meta->buf, &mem[2], length - 2);
1362	meta_buf->bytesused += length + sizeof(meta->ns) + sizeof(meta->sof);
1363
1364	uvc_dbg(stream->dev, FRAME,
1365	"%s(): t-sys %lluns, SOF %u, len %u, flags 0x%x, PTS %u, STC %u frame SOF %u\n",
1366	__func__, ktime_to_ns(time), meta->sof, meta->length,
1367	meta->flags,
1368	has_pts ? *(u32 *)meta->buf : 0,
1369	has_scr ? *(u32 *)scr : 0,
1370	has_scr ? *(u32 *)(scr + 4) & 0x7ff : 0);
1371	}
1372
1373	/* ------------------------------------------------------------------------
1374	* URB handling
1375	*/
1376
1377	/*
1378	* Set error flag for incomplete buffer.
1379	*/
1380	static void uvc_video_validate_buffer(const struct uvc_streaming *stream,
1381	struct uvc_buffer *buf)
1382	{
1383	if (stream->ctrl.dwMaxVideoFrameSize != buf->bytesused &&
1384	!(stream->cur_format->flags & UVC_FMT_FLAG_COMPRESSED))
1385	buf->error = 1;
1386	}
1387
1388	/*
1389	* Completion handler for video URBs.
1390	*/
1391
1392	static void uvc_video_next_buffers(struct uvc_streaming *stream,
1393	struct uvc_buffer **video_buf, struct uvc_buffer **meta_buf)
1394	{
1395	uvc_video_validate_buffer(stream, buf: *video_buf);
1396
1397	if (*meta_buf) {
1398	struct vb2_v4l2_buffer *vb2_meta = &(*meta_buf)->buf;
1399	const struct vb2_v4l2_buffer *vb2_video = &(*video_buf)->buf;
1400
1401	vb2_meta->sequence = vb2_video->sequence;
1402	vb2_meta->field = vb2_video->field;
1403	vb2_meta->vb2_buf.timestamp = vb2_video->vb2_buf.timestamp;
1404
1405	(*meta_buf)->state = UVC_BUF_STATE_READY;
1406	if (!(*meta_buf)->error)
1407	(*meta_buf)->error = (*video_buf)->error;
1408	*meta_buf = uvc_queue_next_buffer(queue: &stream->meta.queue,
1409	buf: *meta_buf);
1410	}
1411	*video_buf = uvc_queue_next_buffer(queue: &stream->queue, buf: *video_buf);
1412	}
1413
1414	static void uvc_video_decode_isoc(struct uvc_urb *uvc_urb,
1415	struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
1416	{
1417	struct urb *urb = uvc_urb->urb;
1418	struct uvc_streaming *stream = uvc_urb->stream;
1419	u8 *mem;
1420	int ret, i;
1421
1422	for (i = 0; i < urb->number_of_packets; ++i) {
1423	if (urb->iso_frame_desc[i].status < 0) {
1424	uvc_dbg(stream->dev, FRAME,
1425	"USB isochronous frame lost (%d)\n",
1426	urb->iso_frame_desc[i].status);
1427	/* Mark the buffer as faulty. */
1428	if (buf != NULL)
1429	buf->error = 1;
1430	continue;
1431	}
1432
1433	/* Decode the payload header. */
1434	mem = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
1435	do {
1436	ret = uvc_video_decode_start(stream, buf, data: mem,
1437	len: urb->iso_frame_desc[i].actual_length);
1438	if (ret == -EAGAIN)
1439	uvc_video_next_buffers(stream, video_buf: &buf, meta_buf: &meta_buf);
1440	} while (ret == -EAGAIN);
1441
1442	if (ret < 0)
1443	continue;
1444
1445	uvc_video_decode_meta(stream, meta_buf, mem, length: ret);
1446
1447	/* Decode the payload data. */
1448	uvc_video_decode_data(uvc_urb, buf, data: mem + ret,
1449	len: urb->iso_frame_desc[i].actual_length - ret);
1450
1451	/* Process the header again. */
1452	uvc_video_decode_end(stream, buf, data: mem,
1453	len: urb->iso_frame_desc[i].actual_length);
1454
1455	if (buf->state == UVC_BUF_STATE_READY)
1456	uvc_video_next_buffers(stream, video_buf: &buf, meta_buf: &meta_buf);
1457	}
1458	}
1459
1460	static void uvc_video_decode_bulk(struct uvc_urb *uvc_urb,
1461	struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
1462	{
1463	struct urb *urb = uvc_urb->urb;
1464	struct uvc_streaming *stream = uvc_urb->stream;
1465	u8 *mem;
1466	int len, ret;
1467
1468	/*
1469	* Ignore ZLPs if they're not part of a frame, otherwise process them
1470	* to trigger the end of payload detection.
1471	*/
1472	if (urb->actual_length == 0 && stream->bulk.header_size == 0)
1473	return;
1474
1475	mem = urb->transfer_buffer;
1476	len = urb->actual_length;
1477	stream->bulk.payload_size += len;
1478
1479	/*
1480	* If the URB is the first of its payload, decode and save the
1481	* header.
1482	*/
1483	if (stream->bulk.header_size == 0 && !stream->bulk.skip_payload) {
1484	do {
1485	ret = uvc_video_decode_start(stream, buf, data: mem, len);
1486	if (ret == -EAGAIN)
1487	uvc_video_next_buffers(stream, video_buf: &buf, meta_buf: &meta_buf);
1488	} while (ret == -EAGAIN);
1489
1490	/* If an error occurred skip the rest of the payload. */
1491	if (ret < 0 || buf == NULL) {
1492	stream->bulk.skip_payload = 1;
1493	} else {
1494	memcpy(stream->bulk.header, mem, ret);
1495	stream->bulk.header_size = ret;
1496
1497	uvc_video_decode_meta(stream, meta_buf, mem, length: ret);
1498
1499	mem += ret;
1500	len -= ret;
1501	}
1502	}
1503
1504	/*
1505	* The buffer queue might have been cancelled while a bulk transfer
1506	* was in progress, so we can reach here with buf equal to NULL. Make
1507	* sure buf is never dereferenced if NULL.
1508	*/
1509
1510	/* Prepare video data for processing. */
1511	if (!stream->bulk.skip_payload && buf != NULL)
1512	uvc_video_decode_data(uvc_urb, buf, data: mem, len);
1513
1514	/*
1515	* Detect the payload end by a URB smaller than the maximum size (or
1516	* a payload size equal to the maximum) and process the header again.
1517	*/
1518	if (urb->actual_length < urb->transfer_buffer_length ||
1519	stream->bulk.payload_size >= stream->bulk.max_payload_size) {
1520	if (!stream->bulk.skip_payload && buf != NULL) {
1521	uvc_video_decode_end(stream, buf, data: stream->bulk.header,
1522	len: stream->bulk.payload_size);
1523	if (buf->state == UVC_BUF_STATE_READY)
1524	uvc_video_next_buffers(stream, video_buf: &buf, meta_buf: &meta_buf);
1525	}
1526
1527	stream->bulk.header_size = 0;
1528	stream->bulk.skip_payload = 0;
1529	stream->bulk.payload_size = 0;
1530	}
1531	}
1532
1533	static void uvc_video_encode_bulk(struct uvc_urb *uvc_urb,
1534	struct uvc_buffer *buf, struct uvc_buffer *meta_buf)
1535	{
1536	struct urb *urb = uvc_urb->urb;
1537	struct uvc_streaming *stream = uvc_urb->stream;
1538
1539	u8 *mem = urb->transfer_buffer;
1540	int len = stream->urb_size, ret;
1541
1542	if (buf == NULL) {
1543	urb->transfer_buffer_length = 0;
1544	return;
1545	}
1546
1547	/* If the URB is the first of its payload, add the header. */
1548	if (stream->bulk.header_size == 0) {
1549	ret = uvc_video_encode_header(stream, buf, data: mem, len);
1550	stream->bulk.header_size = ret;
1551	stream->bulk.payload_size += ret;
1552	mem += ret;
1553	len -= ret;
1554	}
1555
1556	/* Process video data. */
1557	ret = uvc_video_encode_data(stream, buf, data: mem, len);
1558
1559	stream->bulk.payload_size += ret;
1560	len -= ret;
1561
1562	if (buf->bytesused == stream->queue.buf_used ||
1563	stream->bulk.payload_size == stream->bulk.max_payload_size) {
1564	if (buf->bytesused == stream->queue.buf_used) {
1565	stream->queue.buf_used = 0;
1566	buf->state = UVC_BUF_STATE_READY;
1567	buf->buf.sequence = ++stream->sequence;
1568	uvc_queue_next_buffer(queue: &stream->queue, buf);
1569	stream->last_fid ^= UVC_STREAM_FID;
1570	}
1571
1572	stream->bulk.header_size = 0;
1573	stream->bulk.payload_size = 0;
1574	}
1575
1576	urb->transfer_buffer_length = stream->urb_size - len;
1577	}
1578
1579	static void uvc_video_complete(struct urb *urb)
1580	{
1581	struct uvc_urb *uvc_urb = urb->context;
1582	struct uvc_streaming *stream = uvc_urb->stream;
1583	struct uvc_video_queue *queue = &stream->queue;
1584	struct uvc_video_queue *qmeta = &stream->meta.queue;
1585	struct vb2_queue *vb2_qmeta = stream->meta.vdev.queue;
1586	struct uvc_buffer *buf = NULL;
1587	struct uvc_buffer *buf_meta = NULL;
1588	unsigned long flags;
1589	int ret;
1590
1591	switch (urb->status) {
1592	case 0:
1593	break;
1594
1595	default:
1596	dev_warn(&stream->intf->dev,
1597	"Non-zero status (%d) in video completion handler.\n",
1598	urb->status);
1599	fallthrough;
1600	case -ENOENT: /* usb_poison_urb() called. */
1601	if (stream->frozen)
1602	return;
1603	fallthrough;
1604	case -ECONNRESET: /* usb_unlink_urb() called. */
1605	case -ESHUTDOWN: /* The endpoint is being disabled. */
1606	uvc_queue_cancel(queue, disconnect: urb->status == -ESHUTDOWN);
1607	if (vb2_qmeta)
1608	uvc_queue_cancel(queue: qmeta, disconnect: urb->status == -ESHUTDOWN);
1609	return;
1610	}
1611
1612	buf = uvc_queue_get_current_buffer(queue);
1613
1614	if (vb2_qmeta) {
1615	spin_lock_irqsave(&qmeta->irqlock, flags);
1616	if (!list_empty(head: &qmeta->irqqueue))
1617	buf_meta = list_first_entry(&qmeta->irqqueue,
1618	struct uvc_buffer, queue);
1619	spin_unlock_irqrestore(lock: &qmeta->irqlock, flags);
1620	}
1621
1622	/* Re-initialise the URB async work. */
1623	uvc_urb->async_operations = 0;
1624
1625	/* Sync DMA and invalidate vmap range. */
1626	dma_sync_sgtable_for_cpu(dev: uvc_stream_to_dmadev(stream: uvc_urb->stream),
1627	sgt: uvc_urb->sgt, dir: uvc_stream_dir(stream));
1628	invalidate_kernel_vmap_range(vaddr: uvc_urb->buffer,
1629	size: uvc_urb->stream->urb_size);
1630
1631	/*
1632	* Process the URB headers, and optionally queue expensive memcpy tasks
1633	* to be deferred to a work queue.
1634	*/
1635	stream->decode(uvc_urb, buf, buf_meta);
1636
1637	/* If no async work is needed, resubmit the URB immediately. */
1638	if (!uvc_urb->async_operations) {
1639	ret = uvc_submit_urb(uvc_urb, GFP_ATOMIC);
1640	if (ret < 0)
1641	dev_err(&stream->intf->dev,
1642	"Failed to resubmit video URB (%d).\n", ret);
1643	return;
1644	}
1645
1646	queue_work(wq: stream->async_wq, work: &uvc_urb->work);
1647	}
1648
1649	/*
1650	* Free transfer buffers.
1651	*/
1652	static void uvc_free_urb_buffers(struct uvc_streaming *stream)
1653	{
1654	struct device *dma_dev = uvc_stream_to_dmadev(stream);
1655	struct uvc_urb *uvc_urb;
1656
1657	for_each_uvc_urb(uvc_urb, stream) {
1658	if (!uvc_urb->buffer)
1659	continue;
1660
1661	dma_vunmap_noncontiguous(dev: dma_dev, vaddr: uvc_urb->buffer);
1662	dma_free_noncontiguous(dev: dma_dev, size: stream->urb_size, sgt: uvc_urb->sgt,
1663	dir: uvc_stream_dir(stream));
1664
1665	uvc_urb->buffer = NULL;
1666	uvc_urb->sgt = NULL;
1667	}
1668
1669	stream->urb_size = 0;
1670	}
1671
1672	static bool uvc_alloc_urb_buffer(struct uvc_streaming *stream,
1673	struct uvc_urb *uvc_urb, gfp_t gfp_flags)
1674	{
1675	struct device *dma_dev = uvc_stream_to_dmadev(stream);
1676
1677	uvc_urb->sgt = dma_alloc_noncontiguous(dev: dma_dev, size: stream->urb_size,
1678	dir: uvc_stream_dir(stream),
1679	gfp: gfp_flags, attrs: 0);
1680	if (!uvc_urb->sgt)
1681	return false;
1682	uvc_urb->dma = uvc_urb->sgt->sgl->dma_address;
1683
1684	uvc_urb->buffer = dma_vmap_noncontiguous(dev: dma_dev, size: stream->urb_size,
1685	sgt: uvc_urb->sgt);
1686	if (!uvc_urb->buffer) {
1687	dma_free_noncontiguous(dev: dma_dev, size: stream->urb_size,
1688	sgt: uvc_urb->sgt,
1689	dir: uvc_stream_dir(stream));
1690	uvc_urb->sgt = NULL;
1691	return false;
1692	}
1693
1694	return true;
1695	}
1696
1697	/*
1698	* Allocate transfer buffers. This function can be called with buffers
1699	* already allocated when resuming from suspend, in which case it will
1700	* return without touching the buffers.
1701	*
1702	* Limit the buffer size to UVC_MAX_PACKETS bulk/isochronous packets. If the
1703	* system is too low on memory try successively smaller numbers of packets
1704	* until allocation succeeds.
1705	*
1706	* Return the number of allocated packets on success or 0 when out of memory.
1707	*/
1708	static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
1709	unsigned int size, unsigned int psize, gfp_t gfp_flags)
1710	{
1711	unsigned int npackets;
1712	unsigned int i;
1713
1714	/* Buffers are already allocated, bail out. */
1715	if (stream->urb_size)
1716	return stream->urb_size / psize;
1717
1718	/*
1719	* Compute the number of packets. Bulk endpoints might transfer UVC
1720	* payloads across multiple URBs.
1721	*/
1722	npackets = DIV_ROUND_UP(size, psize);
1723	if (npackets > UVC_MAX_PACKETS)
1724	npackets = UVC_MAX_PACKETS;
1725
1726	/* Retry allocations until one succeed. */
1727	for (; npackets > 1; npackets /= 2) {
1728	stream->urb_size = psize * npackets;
1729
1730	for (i = 0; i < UVC_URBS; ++i) {
1731	struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
1732
1733	if (!uvc_alloc_urb_buffer(stream, uvc_urb, gfp_flags)) {
1734	uvc_free_urb_buffers(stream);
1735	break;
1736	}
1737
1738	uvc_urb->stream = stream;
1739	}
1740
1741	if (i == UVC_URBS) {
1742	uvc_dbg(stream->dev, VIDEO,
1743	"Allocated %u URB buffers of %ux%u bytes each\n",
1744	UVC_URBS, npackets, psize);
1745	return npackets;
1746	}
1747	}
1748
1749	uvc_dbg(stream->dev, VIDEO,
1750	"Failed to allocate URB buffers (%u bytes per packet)\n",
1751	psize);
1752	return 0;
1753	}
1754
1755	/*
1756	* Uninitialize isochronous/bulk URBs and free transfer buffers.
1757	*/
1758	static void uvc_video_stop_transfer(struct uvc_streaming *stream,
1759	int free_buffers)
1760	{
1761	struct uvc_urb *uvc_urb;
1762
1763	uvc_video_stats_stop(stream);
1764
1765	/*
1766	* We must poison the URBs rather than kill them to ensure that even
1767	* after the completion handler returns, any asynchronous workqueues
1768	* will be prevented from resubmitting the URBs.
1769	*/
1770	for_each_uvc_urb(uvc_urb, stream)
1771	usb_poison_urb(urb: uvc_urb->urb);
1772
1773	flush_workqueue(stream->async_wq);
1774
1775	for_each_uvc_urb(uvc_urb, stream) {
1776	usb_free_urb(urb: uvc_urb->urb);
1777	uvc_urb->urb = NULL;
1778	}
1779
1780	if (free_buffers)
1781	uvc_free_urb_buffers(stream);
1782	}
1783
1784	/*
1785	* Compute the maximum number of bytes per interval for an endpoint.
1786	*/
1787	u16 uvc_endpoint_max_bpi(struct usb_device *dev, struct usb_host_endpoint *ep)
1788	{
1789	u16 psize;
1790
1791	switch (dev->speed) {
1792	case USB_SPEED_SUPER:
1793	case USB_SPEED_SUPER_PLUS:
1794	return le16_to_cpu(ep->ss_ep_comp.wBytesPerInterval);
1795	default:
1796	psize = usb_endpoint_maxp(epd: &ep->desc);
1797	psize *= usb_endpoint_maxp_mult(epd: &ep->desc);
1798	return psize;
1799	}
1800	}
1801
1802	/*
1803	* Initialize isochronous URBs and allocate transfer buffers. The packet size
1804	* is given by the endpoint.
1805	*/
1806	static int uvc_init_video_isoc(struct uvc_streaming *stream,
1807	struct usb_host_endpoint *ep, gfp_t gfp_flags)
1808	{
1809	struct urb *urb;
1810	struct uvc_urb *uvc_urb;
1811	unsigned int npackets, i;
1812	u16 psize;
1813	u32 size;
1814
1815	psize = uvc_endpoint_max_bpi(dev: stream->dev->udev, ep);
1816	size = stream->ctrl.dwMaxVideoFrameSize;
1817
1818	npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
1819	if (npackets == 0)
1820	return -ENOMEM;
1821
1822	size = npackets * psize;
1823
1824	for_each_uvc_urb(uvc_urb, stream) {
1825	urb = usb_alloc_urb(iso_packets: npackets, mem_flags: gfp_flags);
1826	if (urb == NULL) {
1827	uvc_video_stop_transfer(stream, free_buffers: 1);
1828	return -ENOMEM;
1829	}
1830
1831	urb->dev = stream->dev->udev;
1832	urb->context = uvc_urb;
1833	urb->pipe = usb_rcvisocpipe(stream->dev->udev,
1834	ep->desc.bEndpointAddress);
1835	urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
1836	urb->transfer_dma = uvc_urb->dma;
1837	urb->interval = ep->desc.bInterval;
1838	urb->transfer_buffer = uvc_urb->buffer;
1839	urb->complete = uvc_video_complete;
1840	urb->number_of_packets = npackets;
1841	urb->transfer_buffer_length = size;
1842
1843	for (i = 0; i < npackets; ++i) {
1844	urb->iso_frame_desc[i].offset = i * psize;
1845	urb->iso_frame_desc[i].length = psize;
1846	}
1847
1848	uvc_urb->urb = urb;
1849	}
1850
1851	return 0;
1852	}
1853
1854	/*
1855	* Initialize bulk URBs and allocate transfer buffers. The packet size is
1856	* given by the endpoint.
1857	*/
1858	static int uvc_init_video_bulk(struct uvc_streaming *stream,
1859	struct usb_host_endpoint *ep, gfp_t gfp_flags)
1860	{
1861	struct urb *urb;
1862	struct uvc_urb *uvc_urb;
1863	unsigned int npackets, pipe;
1864	u16 psize;
1865	u32 size;
1866
1867	psize = usb_endpoint_maxp(epd: &ep->desc);
1868	size = stream->ctrl.dwMaxPayloadTransferSize;
1869	stream->bulk.max_payload_size = size;
1870
1871	npackets = uvc_alloc_urb_buffers(stream, size, psize, gfp_flags);
1872	if (npackets == 0)
1873	return -ENOMEM;
1874
1875	size = npackets * psize;
1876
1877	if (usb_endpoint_dir_in(epd: &ep->desc))
1878	pipe = usb_rcvbulkpipe(stream->dev->udev,
1879	ep->desc.bEndpointAddress);
1880	else
1881	pipe = usb_sndbulkpipe(stream->dev->udev,
1882	ep->desc.bEndpointAddress);
1883
1884	if (stream->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
1885	size = 0;
1886
1887	for_each_uvc_urb(uvc_urb, stream) {
1888	urb = usb_alloc_urb(iso_packets: 0, mem_flags: gfp_flags);
1889	if (urb == NULL) {
1890	uvc_video_stop_transfer(stream, free_buffers: 1);
1891	return -ENOMEM;
1892	}
1893
1894	usb_fill_bulk_urb(urb, dev: stream->dev->udev, pipe, transfer_buffer: uvc_urb->buffer,
1895	buffer_length: size, complete_fn: uvc_video_complete, context: uvc_urb);
1896	urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1897	urb->transfer_dma = uvc_urb->dma;
1898
1899	uvc_urb->urb = urb;
1900	}
1901
1902	return 0;
1903	}
1904
1905	/*
1906	* Initialize isochronous/bulk URBs and allocate transfer buffers.
1907	*/
1908	static int uvc_video_start_transfer(struct uvc_streaming *stream,
1909	gfp_t gfp_flags)
1910	{
1911	struct usb_interface *intf = stream->intf;
1912	struct usb_host_endpoint *ep;
1913	struct uvc_urb *uvc_urb;
1914	unsigned int i;
1915	int ret;
1916
1917	stream->sequence = -1;
1918	stream->last_fid = -1;
1919	stream->bulk.header_size = 0;
1920	stream->bulk.skip_payload = 0;
1921	stream->bulk.payload_size = 0;
1922
1923	uvc_video_stats_start(stream);
1924
1925	if (intf->num_altsetting > 1) {
1926	struct usb_host_endpoint *best_ep = NULL;
1927	unsigned int best_psize = UINT_MAX;
1928	unsigned int bandwidth;
1929	unsigned int altsetting;
1930	int intfnum = stream->intfnum;
1931
1932	/* Isochronous endpoint, select the alternate setting. */
1933	bandwidth = stream->ctrl.dwMaxPayloadTransferSize;
1934
1935	if (bandwidth == 0) {
1936	uvc_dbg(stream->dev, VIDEO,
1937	"Device requested null bandwidth, defaulting to lowest\n");
1938	bandwidth = 1;
1939	} else {
1940	uvc_dbg(stream->dev, VIDEO,
1941	"Device requested %u B/frame bandwidth\n",
1942	bandwidth);
1943	}
1944
1945	for (i = 0; i < intf->num_altsetting; ++i) {
1946	struct usb_host_interface *alts;
1947	unsigned int psize;
1948
1949	alts = &intf->altsetting[i];
1950	ep = uvc_find_endpoint(alts,
1951	epaddr: stream->header.bEndpointAddress);
1952	if (ep == NULL)
1953	continue;
1954
1955	/* Check if the bandwidth is high enough. */
1956	psize = uvc_endpoint_max_bpi(dev: stream->dev->udev, ep);
1957	if (psize >= bandwidth && psize < best_psize) {
1958	altsetting = alts->desc.bAlternateSetting;
1959	best_psize = psize;
1960	best_ep = ep;
1961	}
1962	}
1963
1964	if (best_ep == NULL) {
1965	uvc_dbg(stream->dev, VIDEO,
1966	"No fast enough alt setting for requested bandwidth\n");
1967	return -EIO;
1968	}
1969
1970	uvc_dbg(stream->dev, VIDEO,
1971	"Selecting alternate setting %u (%u B/frame bandwidth)\n",
1972	altsetting, best_psize);
1973
1974	/*
1975	* Some devices, namely the Logitech C910 and B910, are unable
1976	* to recover from a USB autosuspend, unless the alternate
1977	* setting of the streaming interface is toggled.
1978	*/
1979	if (stream->dev->quirks & UVC_QUIRK_WAKE_AUTOSUSPEND) {
1980	usb_set_interface(dev: stream->dev->udev, ifnum: intfnum,
1981	alternate: altsetting);
1982	usb_set_interface(dev: stream->dev->udev, ifnum: intfnum, alternate: 0);
1983	}
1984
1985	ret = usb_set_interface(dev: stream->dev->udev, ifnum: intfnum, alternate: altsetting);
1986	if (ret < 0)
1987	return ret;
1988
1989	ret = uvc_init_video_isoc(stream, ep: best_ep, gfp_flags);
1990	} else {
1991	/* Bulk endpoint, proceed to URB initialization. */
1992	ep = uvc_find_endpoint(alts: &intf->altsetting[0],
1993	epaddr: stream->header.bEndpointAddress);
1994	if (ep == NULL)
1995	return -EIO;
1996
1997	/* Reject broken descriptors. */
1998	if (usb_endpoint_maxp(epd: &ep->desc) == 0)
1999	return -EIO;
2000
2001	ret = uvc_init_video_bulk(stream, ep, gfp_flags);
2002	}
2003
2004	if (ret < 0)
2005	return ret;
2006
2007	/* Submit the URBs. */
2008	for_each_uvc_urb(uvc_urb, stream) {
2009	ret = uvc_submit_urb(uvc_urb, mem_flags: gfp_flags);
2010	if (ret < 0) {
2011	dev_err(&stream->intf->dev,
2012	"Failed to submit URB %u (%d).\n",
2013	uvc_urb_index(uvc_urb), ret);
2014	uvc_video_stop_transfer(stream, free_buffers: 1);
2015	return ret;
2016	}
2017	}
2018
2019	/*
2020	* The Logitech C920 temporarily forgets that it should not be adjusting
2021	* Exposure Absolute during init so restore controls to stored values.
2022	*/
2023	if (stream->dev->quirks & UVC_QUIRK_RESTORE_CTRLS_ON_INIT)
2024	uvc_ctrl_restore_values(dev: stream->dev);
2025
2026	return 0;
2027	}
2028
2029	/* --------------------------------------------------------------------------
2030	* Suspend/resume
2031	*/
2032
2033	/*
2034	* Stop streaming without disabling the video queue.
2035	*
2036	* To let userspace applications resume without trouble, we must not touch the
2037	* video buffers in any way. We mark the device as frozen to make sure the URB
2038	* completion handler won't try to cancel the queue when we kill the URBs.
2039	*/
2040	int uvc_video_suspend(struct uvc_streaming *stream)
2041	{
2042	if (!uvc_queue_streaming(queue: &stream->queue))
2043	return 0;
2044
2045	stream->frozen = 1;
2046	uvc_video_stop_transfer(stream, free_buffers: 0);
2047	usb_set_interface(dev: stream->dev->udev, ifnum: stream->intfnum, alternate: 0);
2048	return 0;
2049	}
2050
2051	/*
2052	* Reconfigure the video interface and restart streaming if it was enabled
2053	* before suspend.
2054	*
2055	* If an error occurs, disable the video queue. This will wake all pending
2056	* buffers, making sure userspace applications are notified of the problem
2057	* instead of waiting forever.
2058	*/
2059	int uvc_video_resume(struct uvc_streaming *stream, int reset)
2060	{
2061	int ret;
2062
2063	/*
2064	* If the bus has been reset on resume, set the alternate setting to 0.
2065	* This should be the default value, but some devices crash or otherwise
2066	* misbehave if they don't receive a SET_INTERFACE request before any
2067	* other video control request.
2068	*/
2069	if (reset)
2070	usb_set_interface(dev: stream->dev->udev, ifnum: stream->intfnum, alternate: 0);
2071
2072	stream->frozen = 0;
2073
2074	uvc_video_clock_reset(stream);
2075
2076	if (!uvc_queue_streaming(queue: &stream->queue))
2077	return 0;
2078
2079	ret = uvc_commit_video(stream, probe: &stream->ctrl);
2080	if (ret < 0)
2081	return ret;
2082
2083	return uvc_video_start_transfer(stream, GFP_NOIO);
2084	}
2085
2086	/* ------------------------------------------------------------------------
2087	* Video device
2088	*/
2089
2090	/*
2091	* Initialize the UVC video device by switching to alternate setting 0 and
2092	* retrieve the default format.
2093	*
2094	* Some cameras (namely the Fuji Finepix) set the format and frame
2095	* indexes to zero. The UVC standard doesn't clearly make this a spec
2096	* violation, so try to silently fix the values if possible.
2097	*
2098	* This function is called before registering the device with V4L.
2099	*/
2100	int uvc_video_init(struct uvc_streaming *stream)
2101	{
2102	struct uvc_streaming_control *probe = &stream->ctrl;
2103	const struct uvc_format *format = NULL;
2104	const struct uvc_frame *frame = NULL;
2105	struct uvc_urb *uvc_urb;
2106	unsigned int i;
2107	int ret;
2108
2109	if (stream->nformats == 0) {
2110	dev_info(&stream->intf->dev,
2111	"No supported video formats found.\n");
2112	return -EINVAL;
2113	}
2114
2115	atomic_set(v: &stream->active, i: 0);
2116
2117	/*
2118	* Alternate setting 0 should be the default, yet the XBox Live Vision
2119	* Cam (and possibly other devices) crash or otherwise misbehave if
2120	* they don't receive a SET_INTERFACE request before any other video
2121	* control request.
2122	*/
2123	usb_set_interface(dev: stream->dev->udev, ifnum: stream->intfnum, alternate: 0);
2124
2125	/*
2126	* Set the streaming probe control with default streaming parameters
2127	* retrieved from the device. Webcams that don't support GET_DEF
2128	* requests on the probe control will just keep their current streaming
2129	* parameters.
2130	*/
2131	if (uvc_get_video_ctrl(stream, ctrl: probe, probe: 1, UVC_GET_DEF) == 0)
2132	uvc_set_video_ctrl(stream, ctrl: probe, probe: 1);
2133
2134	/*
2135	* Initialize the streaming parameters with the probe control current
2136	* value. This makes sure SET_CUR requests on the streaming commit
2137	* control will always use values retrieved from a successful GET_CUR
2138	* request on the probe control, as required by the UVC specification.
2139	*/
2140	ret = uvc_get_video_ctrl(stream, ctrl: probe, probe: 1, UVC_GET_CUR);
2141
2142	/*
2143	* Elgato Cam Link 4k can be in a stalled state if the resolution of
2144	* the external source has changed while the firmware initializes.
2145	* Once in this state, the device is useless until it receives a
2146	* USB reset. It has even been observed that the stalled state will
2147	* continue even after unplugging the device.
2148	*/
2149	if (ret == -EPROTO &&
2150	usb_match_one_id(interface: stream->dev->intf, id: &elgato_cam_link_4k)) {
2151	dev_err(&stream->intf->dev, "Elgato Cam Link 4K firmware crash detected\n");
2152	dev_err(&stream->intf->dev, "Resetting the device, unplug and replug to recover\n");
2153	usb_reset_device(dev: stream->dev->udev);
2154	}
2155
2156	if (ret < 0)
2157	return ret;
2158
2159	/*
2160	* Check if the default format descriptor exists. Use the first
2161	* available format otherwise.
2162	*/
2163	for (i = stream->nformats; i > 0; --i) {
2164	format = &stream->formats[i-1];
2165	if (format->index == probe->bFormatIndex)
2166	break;
2167	}
2168
2169	if (format->nframes == 0) {
2170	dev_info(&stream->intf->dev,
2171	"No frame descriptor found for the default format.\n");
2172	return -EINVAL;
2173	}
2174
2175	/*
2176	* Zero bFrameIndex might be correct. Stream-based formats (including
2177	* MPEG-2 TS and DV) do not support frames but have a dummy frame
2178	* descriptor with bFrameIndex set to zero. If the default frame
2179	* descriptor is not found, use the first available frame.
2180	*/
2181	for (i = format->nframes; i > 0; --i) {
2182	frame = &format->frames[i-1];
2183	if (frame->bFrameIndex == probe->bFrameIndex)
2184	break;
2185	}
2186
2187	probe->bFormatIndex = format->index;
2188	probe->bFrameIndex = frame->bFrameIndex;
2189
2190	stream->def_format = format;
2191	stream->cur_format = format;
2192	stream->cur_frame = frame;
2193
2194	/* Select the video decoding function */
2195	if (stream->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
2196	if (stream->dev->quirks & UVC_QUIRK_BUILTIN_ISIGHT)
2197	stream->decode = uvc_video_decode_isight;
2198	else if (stream->intf->num_altsetting > 1)
2199	stream->decode = uvc_video_decode_isoc;
2200	else
2201	stream->decode = uvc_video_decode_bulk;
2202	} else {
2203	if (stream->intf->num_altsetting == 1)
2204	stream->decode = uvc_video_encode_bulk;
2205	else {
2206	dev_info(&stream->intf->dev,
2207	"Isochronous endpoints are not supported for video output devices.\n");
2208	return -EINVAL;
2209	}
2210	}
2211
2212	/* Prepare asynchronous work items. */
2213	for_each_uvc_urb(uvc_urb, stream)
2214	INIT_WORK(&uvc_urb->work, uvc_video_copy_data_work);
2215
2216	return 0;
2217	}
2218
2219	int uvc_video_start_streaming(struct uvc_streaming *stream)
2220	{
2221	int ret;
2222
2223	ret = uvc_video_clock_init(stream);
2224	if (ret < 0)
2225	return ret;
2226
2227	/* Commit the streaming parameters. */
2228	ret = uvc_commit_video(stream, probe: &stream->ctrl);
2229	if (ret < 0)
2230	goto error_commit;
2231
2232	ret = uvc_video_start_transfer(stream, GFP_KERNEL);
2233	if (ret < 0)
2234	goto error_video;
2235
2236	return 0;
2237
2238	error_video:
2239	usb_set_interface(dev: stream->dev->udev, ifnum: stream->intfnum, alternate: 0);
2240	error_commit:
2241	uvc_video_clock_cleanup(stream);
2242
2243	return ret;
2244	}
2245
2246	void uvc_video_stop_streaming(struct uvc_streaming *stream)
2247	{
2248	uvc_video_stop_transfer(stream, free_buffers: 1);
2249
2250	if (stream->intf->num_altsetting > 1) {
2251	usb_set_interface(dev: stream->dev->udev, ifnum: stream->intfnum, alternate: 0);
2252	} else {
2253	/*
2254	* UVC doesn't specify how to inform a bulk-based device
2255	* when the video stream is stopped. Windows sends a
2256	* CLEAR_FEATURE(HALT) request to the video streaming
2257	* bulk endpoint, mimic the same behaviour.
2258	*/
2259	unsigned int epnum = stream->header.bEndpointAddress
2260	& USB_ENDPOINT_NUMBER_MASK;
2261	unsigned int dir = stream->header.bEndpointAddress
2262	& USB_ENDPOINT_DIR_MASK;
2263	unsigned int pipe;
2264
2265	pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir;
2266	usb_clear_halt(dev: stream->dev->udev, pipe);
2267	}
2268
2269	uvc_video_clock_cleanup(stream);
2270	}
2271