1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2012 Red Hat |
4 | * based in parts on udlfb.c: |
5 | * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it> |
6 | * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com> |
7 | * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com> |
8 | */ |
9 | |
10 | #include <asm/unaligned.h> |
11 | |
12 | #include "udl_drv.h" |
13 | #include "udl_proto.h" |
14 | |
15 | #define MAX_CMD_PIXELS 255 |
16 | |
17 | #define 7 |
18 | #define MIN_RLX_PIX_BYTES 4 |
19 | #define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES) |
20 | |
21 | #define 6 |
22 | #define MIN_RLE_PIX_BYTES 3 |
23 | #define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES) |
24 | |
25 | #define 6 |
26 | #define MIN_RAW_PIX_BYTES 2 |
27 | #define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES) |
28 | |
29 | static inline u16 pixel32_to_be16(const uint32_t pixel) |
30 | { |
31 | return (((pixel >> 3) & 0x001f) | |
32 | ((pixel >> 5) & 0x07e0) | |
33 | ((pixel >> 8) & 0xf800)); |
34 | } |
35 | |
36 | static inline u16 get_pixel_val16(const uint8_t *pixel, int log_bpp) |
37 | { |
38 | u16 pixel_val16; |
39 | if (log_bpp == 1) |
40 | pixel_val16 = *(const uint16_t *)pixel; |
41 | else |
42 | pixel_val16 = pixel32_to_be16(pixel: *(const uint32_t *)pixel); |
43 | return pixel_val16; |
44 | } |
45 | |
46 | /* |
47 | * Render a command stream for an encoded horizontal line segment of pixels. |
48 | * |
49 | * A command buffer holds several commands. |
50 | * It always begins with a fresh command header |
51 | * (the protocol doesn't require this, but we enforce it to allow |
52 | * multiple buffers to be potentially encoded and sent in parallel). |
53 | * A single command encodes one contiguous horizontal line of pixels |
54 | * |
55 | * The function relies on the client to do all allocation, so that |
56 | * rendering can be done directly to output buffers (e.g. USB URBs). |
57 | * The function fills the supplied command buffer, providing information |
58 | * on where it left off, so the client may call in again with additional |
59 | * buffers if the line will take several buffers to complete. |
60 | * |
61 | * A single command can transmit a maximum of 256 pixels, |
62 | * regardless of the compression ratio (protocol design limit). |
63 | * To the hardware, 0 for a size byte means 256 |
64 | * |
65 | * Rather than 256 pixel commands which are either rl or raw encoded, |
66 | * the rlx command simply assumes alternating raw and rl spans within one cmd. |
67 | * This has a slightly larger header overhead, but produces more even results. |
68 | * It also processes all data (read and write) in a single pass. |
69 | * Performance benchmarks of common cases show it having just slightly better |
70 | * compression than 256 pixel raw or rle commands, with similar CPU consumpion. |
71 | * But for very rl friendly data, will compress not quite as well. |
72 | */ |
73 | static void udl_compress_hline16( |
74 | const u8 **pixel_start_ptr, |
75 | const u8 *const pixel_end, |
76 | uint32_t *device_address_ptr, |
77 | uint8_t **command_buffer_ptr, |
78 | const uint8_t *const cmd_buffer_end, int log_bpp) |
79 | { |
80 | const int bpp = 1 << log_bpp; |
81 | const u8 *pixel = *pixel_start_ptr; |
82 | uint32_t dev_addr = *device_address_ptr; |
83 | uint8_t *cmd = *command_buffer_ptr; |
84 | |
85 | while ((pixel_end > pixel) && |
86 | (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) { |
87 | uint8_t *raw_pixels_count_byte = NULL; |
88 | uint8_t *cmd_pixels_count_byte = NULL; |
89 | const u8 *raw_pixel_start = NULL; |
90 | const u8 *cmd_pixel_start, *cmd_pixel_end = NULL; |
91 | uint16_t pixel_val16; |
92 | |
93 | *cmd++ = UDL_MSG_BULK; |
94 | *cmd++ = UDL_CMD_WRITERLX16; |
95 | *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF); |
96 | *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF); |
97 | *cmd++ = (uint8_t) ((dev_addr) & 0xFF); |
98 | |
99 | cmd_pixels_count_byte = cmd++; /* we'll know this later */ |
100 | cmd_pixel_start = pixel; |
101 | |
102 | raw_pixels_count_byte = cmd++; /* we'll know this later */ |
103 | raw_pixel_start = pixel; |
104 | |
105 | cmd_pixel_end = pixel + (min3(MAX_CMD_PIXELS + 1UL, |
106 | (unsigned long)(pixel_end - pixel) >> log_bpp, |
107 | (unsigned long)(cmd_buffer_end - 1 - cmd) / 2) << log_bpp); |
108 | |
109 | pixel_val16 = get_pixel_val16(pixel, log_bpp); |
110 | |
111 | while (pixel < cmd_pixel_end) { |
112 | const u8 *const start = pixel; |
113 | const uint16_t repeating_pixel_val16 = pixel_val16; |
114 | |
115 | put_unaligned_be16(val: pixel_val16, p: cmd); |
116 | |
117 | cmd += 2; |
118 | pixel += bpp; |
119 | |
120 | while (pixel < cmd_pixel_end) { |
121 | pixel_val16 = get_pixel_val16(pixel, log_bpp); |
122 | if (pixel_val16 != repeating_pixel_val16) |
123 | break; |
124 | pixel += bpp; |
125 | } |
126 | |
127 | if (unlikely(pixel > start + bpp)) { |
128 | /* go back and fill in raw pixel count */ |
129 | *raw_pixels_count_byte = (((start - |
130 | raw_pixel_start) >> log_bpp) + 1) & 0xFF; |
131 | |
132 | /* immediately after raw data is repeat byte */ |
133 | *cmd++ = (((pixel - start) >> log_bpp) - 1) & 0xFF; |
134 | |
135 | /* Then start another raw pixel span */ |
136 | raw_pixel_start = pixel; |
137 | raw_pixels_count_byte = cmd++; |
138 | } |
139 | } |
140 | |
141 | if (pixel > raw_pixel_start) { |
142 | /* finalize last RAW span */ |
143 | *raw_pixels_count_byte = ((pixel - raw_pixel_start) >> log_bpp) & 0xFF; |
144 | } else { |
145 | /* undo unused byte */ |
146 | cmd--; |
147 | } |
148 | |
149 | *cmd_pixels_count_byte = ((pixel - cmd_pixel_start) >> log_bpp) & 0xFF; |
150 | dev_addr += ((pixel - cmd_pixel_start) >> log_bpp) * 2; |
151 | } |
152 | |
153 | if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) { |
154 | /* Fill leftover bytes with no-ops */ |
155 | if (cmd_buffer_end > cmd) |
156 | memset(cmd, UDL_MSG_BULK, cmd_buffer_end - cmd); |
157 | cmd = (uint8_t *) cmd_buffer_end; |
158 | } |
159 | |
160 | *command_buffer_ptr = cmd; |
161 | *pixel_start_ptr = pixel; |
162 | *device_address_ptr = dev_addr; |
163 | |
164 | return; |
165 | } |
166 | |
167 | /* |
168 | * There are 3 copies of every pixel: The front buffer that the fbdev |
169 | * client renders to, the actual framebuffer across the USB bus in hardware |
170 | * (that we can only write to, slowly, and can never read), and (optionally) |
171 | * our shadow copy that tracks what's been sent to that hardware buffer. |
172 | */ |
173 | int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr, |
174 | const char *front, char **urb_buf_ptr, |
175 | u32 byte_offset, u32 device_byte_offset, |
176 | u32 byte_width) |
177 | { |
178 | const u8 *line_start, *line_end, *next_pixel; |
179 | u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2; |
180 | struct urb *urb = *urb_ptr; |
181 | u8 *cmd = *urb_buf_ptr; |
182 | u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length; |
183 | |
184 | if (WARN_ON(!(log_bpp == 1 || log_bpp == 2))) { |
185 | /* need to finish URB at error from this function */ |
186 | udl_urb_completion(urb); |
187 | return -EINVAL; |
188 | } |
189 | |
190 | line_start = (u8 *) (front + byte_offset); |
191 | next_pixel = line_start; |
192 | line_end = next_pixel + byte_width; |
193 | |
194 | while (next_pixel < line_end) { |
195 | |
196 | udl_compress_hline16(pixel_start_ptr: &next_pixel, |
197 | pixel_end: line_end, device_address_ptr: &base16, |
198 | command_buffer_ptr: (u8 **) &cmd, cmd_buffer_end: (u8 *) cmd_end, log_bpp); |
199 | |
200 | if (cmd >= cmd_end) { |
201 | int len = cmd - (u8 *) urb->transfer_buffer; |
202 | int ret = udl_submit_urb(dev, urb, len); |
203 | if (ret) |
204 | return ret; |
205 | urb = udl_get_urb(dev); |
206 | if (!urb) |
207 | return -EAGAIN; |
208 | *urb_ptr = urb; |
209 | cmd = urb->transfer_buffer; |
210 | cmd_end = &cmd[urb->transfer_buffer_length]; |
211 | } |
212 | } |
213 | |
214 | *urb_buf_ptr = cmd; |
215 | |
216 | return 0; |
217 | } |
218 | |