1// SPDX-License-Identifier: GPL-2.0+
2
3#include <linux/crc32.h>
4
5#include <drm/drm_atomic.h>
6#include <drm/drm_atomic_helper.h>
7#include <drm/drm_blend.h>
8#include <drm/drm_fourcc.h>
9#include <drm/drm_fixed.h>
10#include <drm/drm_gem_framebuffer_helper.h>
11#include <drm/drm_vblank.h>
12#include <linux/minmax.h>
13
14#include "vkms_drv.h"
15
16static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
17{
18 u32 new_color;
19
20 new_color = (src * 0xffff + dst * (0xffff - alpha));
21
22 return DIV_ROUND_CLOSEST(new_color, 0xffff);
23}
24
25/**
26 * pre_mul_alpha_blend - alpha blending equation
27 * @frame_info: Source framebuffer's metadata
28 * @stage_buffer: The line with the pixels from src_plane
29 * @output_buffer: A line buffer that receives all the blends output
30 *
31 * Using the information from the `frame_info`, this blends only the
32 * necessary pixels from the `stage_buffer` to the `output_buffer`
33 * using premultiplied blend formula.
34 *
35 * The current DRM assumption is that pixel color values have been already
36 * pre-multiplied with the alpha channel values. See more
37 * drm_plane_create_blend_mode_property(). Also, this formula assumes a
38 * completely opaque background.
39 */
40static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
41 struct line_buffer *stage_buffer,
42 struct line_buffer *output_buffer)
43{
44 int x_dst = frame_info->dst.x1;
45 struct pixel_argb_u16 *out = output_buffer->pixels + x_dst;
46 struct pixel_argb_u16 *in = stage_buffer->pixels;
47 int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
48 stage_buffer->n_pixels);
49
50 for (int x = 0; x < x_limit; x++) {
51 out[x].a = (u16)0xffff;
52 out[x].r = pre_mul_blend_channel(src: in[x].r, dst: out[x].r, alpha: in[x].a);
53 out[x].g = pre_mul_blend_channel(src: in[x].g, dst: out[x].g, alpha: in[x].a);
54 out[x].b = pre_mul_blend_channel(src: in[x].b, dst: out[x].b, alpha: in[x].a);
55 }
56}
57
58static int get_y_pos(struct vkms_frame_info *frame_info, int y)
59{
60 if (frame_info->rotation & DRM_MODE_REFLECT_Y)
61 return drm_rect_height(r: &frame_info->rotated) - y - 1;
62
63 switch (frame_info->rotation & DRM_MODE_ROTATE_MASK) {
64 case DRM_MODE_ROTATE_90:
65 return frame_info->rotated.x2 - y - 1;
66 case DRM_MODE_ROTATE_270:
67 return y + frame_info->rotated.x1;
68 default:
69 return y;
70 }
71}
72
73static bool check_limit(struct vkms_frame_info *frame_info, int pos)
74{
75 if (drm_rotation_90_or_270(rotation: frame_info->rotation)) {
76 if (pos >= 0 && pos < drm_rect_width(r: &frame_info->rotated))
77 return true;
78 } else {
79 if (pos >= frame_info->rotated.y1 && pos < frame_info->rotated.y2)
80 return true;
81 }
82
83 return false;
84}
85
86static void fill_background(const struct pixel_argb_u16 *background_color,
87 struct line_buffer *output_buffer)
88{
89 for (size_t i = 0; i < output_buffer->n_pixels; i++)
90 output_buffer->pixels[i] = *background_color;
91}
92
93// lerp(a, b, t) = a + (b - a) * t
94static u16 lerp_u16(u16 a, u16 b, s64 t)
95{
96 s64 a_fp = drm_int2fixp(a);
97 s64 b_fp = drm_int2fixp(a: b);
98
99 s64 delta = drm_fixp_mul(a: b_fp - a_fp, b: t);
100
101 return drm_fixp2int(a: a_fp + delta);
102}
103
104static s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value)
105{
106 s64 color_channel_fp = drm_int2fixp(a: channel_value);
107
108 return drm_fixp_mul(a: color_channel_fp, b: lut->channel_value2index_ratio);
109}
110
111/*
112 * This enum is related to the positions of the variables inside
113 * `struct drm_color_lut`, so the order of both needs to be the same.
114 */
115enum lut_channel {
116 LUT_RED = 0,
117 LUT_GREEN,
118 LUT_BLUE,
119 LUT_RESERVED
120};
121
122static u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 channel_value,
123 enum lut_channel channel)
124{
125 s64 lut_index = get_lut_index(lut, channel_value);
126 u16 *floor_lut_value, *ceil_lut_value;
127 u16 floor_channel_value, ceil_channel_value;
128
129 /*
130 * This checks if `struct drm_color_lut` has any gap added by the compiler
131 * between the struct fields.
132 */
133 static_assert(sizeof(struct drm_color_lut) == sizeof(__u16) * 4);
134
135 floor_lut_value = (__u16 *)&lut->base[drm_fixp2int(a: lut_index)];
136 if (drm_fixp2int(a: lut_index) == (lut->lut_length - 1))
137 /* We're at the end of the LUT array, use same value for ceil and floor */
138 ceil_lut_value = floor_lut_value;
139 else
140 ceil_lut_value = (__u16 *)&lut->base[drm_fixp2int_ceil(a: lut_index)];
141
142 floor_channel_value = floor_lut_value[channel];
143 ceil_channel_value = ceil_lut_value[channel];
144
145 return lerp_u16(a: floor_channel_value, b: ceil_channel_value,
146 t: lut_index & DRM_FIXED_DECIMAL_MASK);
147}
148
149static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buffer *output_buffer)
150{
151 if (!crtc_state->gamma_lut.base)
152 return;
153
154 if (!crtc_state->gamma_lut.lut_length)
155 return;
156
157 for (size_t x = 0; x < output_buffer->n_pixels; x++) {
158 struct pixel_argb_u16 *pixel = &output_buffer->pixels[x];
159
160 pixel->r = apply_lut_to_channel_value(lut: &crtc_state->gamma_lut, channel_value: pixel->r, channel: LUT_RED);
161 pixel->g = apply_lut_to_channel_value(lut: &crtc_state->gamma_lut, channel_value: pixel->g, channel: LUT_GREEN);
162 pixel->b = apply_lut_to_channel_value(lut: &crtc_state->gamma_lut, channel_value: pixel->b, channel: LUT_BLUE);
163 }
164}
165
166/**
167 * blend - blend the pixels from all planes and compute crc
168 * @wb: The writeback frame buffer metadata
169 * @crtc_state: The crtc state
170 * @crc32: The crc output of the final frame
171 * @output_buffer: A buffer of a row that will receive the result of the blend(s)
172 * @stage_buffer: The line with the pixels from plane being blend to the output
173 * @row_size: The size, in bytes, of a single row
174 *
175 * This function blends the pixels (Using the `pre_mul_alpha_blend`)
176 * from all planes, calculates the crc32 of the output from the former step,
177 * and, if necessary, convert and store the output to the writeback buffer.
178 */
179static void blend(struct vkms_writeback_job *wb,
180 struct vkms_crtc_state *crtc_state,
181 u32 *crc32, struct line_buffer *stage_buffer,
182 struct line_buffer *output_buffer, size_t row_size)
183{
184 struct vkms_plane_state **plane = crtc_state->active_planes;
185 u32 n_active_planes = crtc_state->num_active_planes;
186 int y_pos;
187
188 const struct pixel_argb_u16 background_color = { .a = 0xffff };
189
190 size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
191
192 for (size_t y = 0; y < crtc_y_limit; y++) {
193 fill_background(background_color: &background_color, output_buffer);
194
195 /* The active planes are composed associatively in z-order. */
196 for (size_t i = 0; i < n_active_planes; i++) {
197 y_pos = get_y_pos(frame_info: plane[i]->frame_info, y);
198
199 if (!check_limit(frame_info: plane[i]->frame_info, pos: y_pos))
200 continue;
201
202 vkms_compose_row(stage_buffer, plane: plane[i], y: y_pos);
203 pre_mul_alpha_blend(frame_info: plane[i]->frame_info, stage_buffer,
204 output_buffer);
205 }
206
207 apply_lut(crtc_state, output_buffer);
208
209 *crc32 = crc32_le(crc: *crc32, p: (void *)output_buffer->pixels, len: row_size);
210
211 if (wb)
212 vkms_writeback_row(wb, src_buffer: output_buffer, y: y_pos);
213 }
214}
215
216static int check_format_funcs(struct vkms_crtc_state *crtc_state,
217 struct vkms_writeback_job *active_wb)
218{
219 struct vkms_plane_state **planes = crtc_state->active_planes;
220 u32 n_active_planes = crtc_state->num_active_planes;
221
222 for (size_t i = 0; i < n_active_planes; i++)
223 if (!planes[i]->pixel_read)
224 return -1;
225
226 if (active_wb && !active_wb->pixel_write)
227 return -1;
228
229 return 0;
230}
231
232static int check_iosys_map(struct vkms_crtc_state *crtc_state)
233{
234 struct vkms_plane_state **plane_state = crtc_state->active_planes;
235 u32 n_active_planes = crtc_state->num_active_planes;
236
237 for (size_t i = 0; i < n_active_planes; i++)
238 if (iosys_map_is_null(map: &plane_state[i]->frame_info->map[0]))
239 return -1;
240
241 return 0;
242}
243
244static int compose_active_planes(struct vkms_writeback_job *active_wb,
245 struct vkms_crtc_state *crtc_state,
246 u32 *crc32)
247{
248 size_t line_width, pixel_size = sizeof(struct pixel_argb_u16);
249 struct line_buffer output_buffer, stage_buffer;
250 int ret = 0;
251
252 /*
253 * This check exists so we can call `crc32_le` for the entire line
254 * instead doing it for each channel of each pixel in case
255 * `struct `pixel_argb_u16` had any gap added by the compiler
256 * between the struct fields.
257 */
258 static_assert(sizeof(struct pixel_argb_u16) == 8);
259
260 if (WARN_ON(check_iosys_map(crtc_state)))
261 return -EINVAL;
262
263 if (WARN_ON(check_format_funcs(crtc_state, active_wb)))
264 return -EINVAL;
265
266 line_width = crtc_state->base.crtc->mode.hdisplay;
267 stage_buffer.n_pixels = line_width;
268 output_buffer.n_pixels = line_width;
269
270 stage_buffer.pixels = kvmalloc(size: line_width * pixel_size, GFP_KERNEL);
271 if (!stage_buffer.pixels) {
272 DRM_ERROR("Cannot allocate memory for the output line buffer");
273 return -ENOMEM;
274 }
275
276 output_buffer.pixels = kvmalloc(size: line_width * pixel_size, GFP_KERNEL);
277 if (!output_buffer.pixels) {
278 DRM_ERROR("Cannot allocate memory for intermediate line buffer");
279 ret = -ENOMEM;
280 goto free_stage_buffer;
281 }
282
283 blend(wb: active_wb, crtc_state, crc32, stage_buffer: &stage_buffer,
284 output_buffer: &output_buffer, row_size: line_width * pixel_size);
285
286 kvfree(addr: output_buffer.pixels);
287free_stage_buffer:
288 kvfree(addr: stage_buffer.pixels);
289
290 return ret;
291}
292
293/**
294 * vkms_composer_worker - ordered work_struct to compute CRC
295 *
296 * @work: work_struct
297 *
298 * Work handler for composing and computing CRCs. work_struct scheduled in
299 * an ordered workqueue that's periodically scheduled to run by
300 * vkms_vblank_simulate() and flushed at vkms_atomic_commit_tail().
301 */
302void vkms_composer_worker(struct work_struct *work)
303{
304 struct vkms_crtc_state *crtc_state = container_of(work,
305 struct vkms_crtc_state,
306 composer_work);
307 struct drm_crtc *crtc = crtc_state->base.crtc;
308 struct vkms_writeback_job *active_wb = crtc_state->active_writeback;
309 struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
310 bool crc_pending, wb_pending;
311 u64 frame_start, frame_end;
312 u32 crc32 = 0;
313 int ret;
314
315 spin_lock_irq(lock: &out->composer_lock);
316 frame_start = crtc_state->frame_start;
317 frame_end = crtc_state->frame_end;
318 crc_pending = crtc_state->crc_pending;
319 wb_pending = crtc_state->wb_pending;
320 crtc_state->frame_start = 0;
321 crtc_state->frame_end = 0;
322 crtc_state->crc_pending = false;
323
324 if (crtc->state->gamma_lut) {
325 s64 max_lut_index_fp;
326 s64 u16_max_fp = drm_int2fixp(a: 0xffff);
327
328 crtc_state->gamma_lut.base = (struct drm_color_lut *)crtc->state->gamma_lut->data;
329 crtc_state->gamma_lut.lut_length =
330 crtc->state->gamma_lut->length / sizeof(struct drm_color_lut);
331 max_lut_index_fp = drm_int2fixp(a: crtc_state->gamma_lut.lut_length - 1);
332 crtc_state->gamma_lut.channel_value2index_ratio = drm_fixp_div(a: max_lut_index_fp,
333 b: u16_max_fp);
334
335 } else {
336 crtc_state->gamma_lut.base = NULL;
337 }
338
339 spin_unlock_irq(lock: &out->composer_lock);
340
341 /*
342 * We raced with the vblank hrtimer and previous work already computed
343 * the crc, nothing to do.
344 */
345 if (!crc_pending)
346 return;
347
348 if (wb_pending)
349 ret = compose_active_planes(active_wb, crtc_state, crc32: &crc32);
350 else
351 ret = compose_active_planes(NULL, crtc_state, crc32: &crc32);
352
353 if (ret)
354 return;
355
356 if (wb_pending) {
357 drm_writeback_signal_completion(wb_connector: &out->wb_connector, status: 0);
358 spin_lock_irq(lock: &out->composer_lock);
359 crtc_state->wb_pending = false;
360 spin_unlock_irq(lock: &out->composer_lock);
361 }
362
363 /*
364 * The worker can fall behind the vblank hrtimer, make sure we catch up.
365 */
366 while (frame_start <= frame_end)
367 drm_crtc_add_crc_entry(crtc, has_frame: true, frame: frame_start++, crcs: &crc32);
368}
369
370static const char * const pipe_crc_sources[] = {"auto"};
371
372const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
373 size_t *count)
374{
375 *count = ARRAY_SIZE(pipe_crc_sources);
376 return pipe_crc_sources;
377}
378
379static int vkms_crc_parse_source(const char *src_name, bool *enabled)
380{
381 int ret = 0;
382
383 if (!src_name) {
384 *enabled = false;
385 } else if (strcmp(src_name, "auto") == 0) {
386 *enabled = true;
387 } else {
388 *enabled = false;
389 ret = -EINVAL;
390 }
391
392 return ret;
393}
394
395int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
396 size_t *values_cnt)
397{
398 bool enabled;
399
400 if (vkms_crc_parse_source(src_name, enabled: &enabled) < 0) {
401 DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
402 return -EINVAL;
403 }
404
405 *values_cnt = 1;
406
407 return 0;
408}
409
410void vkms_set_composer(struct vkms_output *out, bool enabled)
411{
412 bool old_enabled;
413
414 if (enabled)
415 drm_crtc_vblank_get(crtc: &out->crtc);
416
417 spin_lock_irq(lock: &out->lock);
418 old_enabled = out->composer_enabled;
419 out->composer_enabled = enabled;
420 spin_unlock_irq(lock: &out->lock);
421
422 if (old_enabled)
423 drm_crtc_vblank_put(crtc: &out->crtc);
424}
425
426int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
427{
428 struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
429 bool enabled = false;
430 int ret = 0;
431
432 ret = vkms_crc_parse_source(src_name, enabled: &enabled);
433
434 vkms_set_composer(out, enabled);
435
436 return ret;
437}
438

source code of linux/drivers/gpu/drm/vkms/vkms_composer.c