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 16 static 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 */ 40 static 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(in[x].r, out[x].r, in[x].a); 53 out[x].g = pre_mul_blend_channel(in[x].g, out[x].g, in[x].a); 54 out[x].b = pre_mul_blend_channel(in[x].b, out[x].b, in[x].a); 55 } 56 } 57 58 static 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(&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 73 static bool check_limit(struct vkms_frame_info *frame_info, int pos) 74 { 75 if (drm_rotation_90_or_270(frame_info->rotation)) { 76 if (pos >= 0 && pos < drm_rect_width(&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 86 static 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 94 static u16 lerp_u16(u16 a, u16 b, s64 t) 95 { 96 s64 a_fp = drm_int2fixp(a); 97 s64 b_fp = drm_int2fixp(b); 98 99 s64 delta = drm_fixp_mul(b_fp - a_fp, t); 100 101 return drm_fixp2int(a_fp + delta); 102 } 103 104 static s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value) 105 { 106 s64 color_channel_fp = drm_int2fixp(channel_value); 107 108 return drm_fixp_mul(color_channel_fp, 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 */ 115 enum lut_channel { 116 LUT_RED = 0, 117 LUT_GREEN, 118 LUT_BLUE, 119 LUT_RESERVED 120 }; 121 122 static 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(lut_index)]; 136 if (drm_fixp2int(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(lut_index)]; 141 142 floor_channel_value = floor_lut_value[channel]; 143 ceil_channel_value = ceil_lut_value[channel]; 144 145 return lerp_u16(floor_channel_value, ceil_channel_value, 146 lut_index & DRM_FIXED_DECIMAL_MASK); 147 } 148 149 static 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(&crtc_state->gamma_lut, pixel->r, LUT_RED); 161 pixel->g = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->g, LUT_GREEN); 162 pixel->b = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->b, 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 */ 179 static 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.mode.vdisplay; 191 192 /* 193 * The planes are composed line-by-line to avoid heavy memory usage. It is a necessary 194 * complexity to avoid poor blending performance. 195 * 196 * The function vkms_compose_row() is used to read a line, pixel-by-pixel, into the staging 197 * buffer. 198 */ 199 for (size_t y = 0; y < crtc_y_limit; y++) { 200 fill_background(&background_color, output_buffer); 201 202 /* The active planes are composed associatively in z-order. */ 203 for (size_t i = 0; i < n_active_planes; i++) { 204 y_pos = get_y_pos(plane[i]->frame_info, y); 205 206 if (!check_limit(plane[i]->frame_info, y_pos)) 207 continue; 208 209 vkms_compose_row(stage_buffer, plane[i], y_pos); 210 pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer, 211 output_buffer); 212 } 213 214 apply_lut(crtc_state, output_buffer); 215 216 *crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size); 217 218 if (wb) 219 vkms_writeback_row(wb, output_buffer, y_pos); 220 } 221 } 222 223 static int check_format_funcs(struct vkms_crtc_state *crtc_state, 224 struct vkms_writeback_job *active_wb) 225 { 226 struct vkms_plane_state **planes = crtc_state->active_planes; 227 u32 n_active_planes = crtc_state->num_active_planes; 228 229 for (size_t i = 0; i < n_active_planes; i++) 230 if (!planes[i]->pixel_read) 231 return -1; 232 233 if (active_wb && !active_wb->pixel_write) 234 return -1; 235 236 return 0; 237 } 238 239 static int check_iosys_map(struct vkms_crtc_state *crtc_state) 240 { 241 struct vkms_plane_state **plane_state = crtc_state->active_planes; 242 u32 n_active_planes = crtc_state->num_active_planes; 243 244 for (size_t i = 0; i < n_active_planes; i++) 245 if (iosys_map_is_null(&plane_state[i]->frame_info->map[0])) 246 return -1; 247 248 return 0; 249 } 250 251 static int compose_active_planes(struct vkms_writeback_job *active_wb, 252 struct vkms_crtc_state *crtc_state, 253 u32 *crc32) 254 { 255 size_t line_width, pixel_size = sizeof(struct pixel_argb_u16); 256 struct line_buffer output_buffer, stage_buffer; 257 int ret = 0; 258 259 /* 260 * This check exists so we can call `crc32_le` for the entire line 261 * instead doing it for each channel of each pixel in case 262 * `struct `pixel_argb_u16` had any gap added by the compiler 263 * between the struct fields. 264 */ 265 static_assert(sizeof(struct pixel_argb_u16) == 8); 266 267 if (WARN_ON(check_iosys_map(crtc_state))) 268 return -EINVAL; 269 270 if (WARN_ON(check_format_funcs(crtc_state, active_wb))) 271 return -EINVAL; 272 273 line_width = crtc_state->base.mode.hdisplay; 274 stage_buffer.n_pixels = line_width; 275 output_buffer.n_pixels = line_width; 276 277 stage_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL); 278 if (!stage_buffer.pixels) { 279 DRM_ERROR("Cannot allocate memory for the output line buffer"); 280 return -ENOMEM; 281 } 282 283 output_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL); 284 if (!output_buffer.pixels) { 285 DRM_ERROR("Cannot allocate memory for intermediate line buffer"); 286 ret = -ENOMEM; 287 goto free_stage_buffer; 288 } 289 290 blend(active_wb, crtc_state, crc32, &stage_buffer, 291 &output_buffer, line_width * pixel_size); 292 293 kvfree(output_buffer.pixels); 294 free_stage_buffer: 295 kvfree(stage_buffer.pixels); 296 297 return ret; 298 } 299 300 /** 301 * vkms_composer_worker - ordered work_struct to compute CRC 302 * 303 * @work: work_struct 304 * 305 * Work handler for composing and computing CRCs. work_struct scheduled in 306 * an ordered workqueue that's periodically scheduled to run by 307 * vkms_vblank_simulate() and flushed at vkms_atomic_commit_tail(). 308 */ 309 void vkms_composer_worker(struct work_struct *work) 310 { 311 struct vkms_crtc_state *crtc_state = container_of(work, 312 struct vkms_crtc_state, 313 composer_work); 314 struct drm_crtc *crtc = crtc_state->base.crtc; 315 struct vkms_writeback_job *active_wb = crtc_state->active_writeback; 316 struct vkms_output *out = drm_crtc_to_vkms_output(crtc); 317 bool crc_pending, wb_pending; 318 u64 frame_start, frame_end; 319 u32 crc32 = 0; 320 int ret; 321 322 spin_lock_irq(&out->composer_lock); 323 frame_start = crtc_state->frame_start; 324 frame_end = crtc_state->frame_end; 325 crc_pending = crtc_state->crc_pending; 326 wb_pending = crtc_state->wb_pending; 327 crtc_state->frame_start = 0; 328 crtc_state->frame_end = 0; 329 crtc_state->crc_pending = false; 330 331 if (crtc->state->gamma_lut) { 332 s64 max_lut_index_fp; 333 s64 u16_max_fp = drm_int2fixp(0xffff); 334 335 crtc_state->gamma_lut.base = (struct drm_color_lut *)crtc->state->gamma_lut->data; 336 crtc_state->gamma_lut.lut_length = 337 crtc->state->gamma_lut->length / sizeof(struct drm_color_lut); 338 max_lut_index_fp = drm_int2fixp(crtc_state->gamma_lut.lut_length - 1); 339 crtc_state->gamma_lut.channel_value2index_ratio = drm_fixp_div(max_lut_index_fp, 340 u16_max_fp); 341 342 } else { 343 crtc_state->gamma_lut.base = NULL; 344 } 345 346 spin_unlock_irq(&out->composer_lock); 347 348 /* 349 * We raced with the vblank hrtimer and previous work already computed 350 * the crc, nothing to do. 351 */ 352 if (!crc_pending) 353 return; 354 355 if (wb_pending) 356 ret = compose_active_planes(active_wb, crtc_state, &crc32); 357 else 358 ret = compose_active_planes(NULL, crtc_state, &crc32); 359 360 if (ret) 361 return; 362 363 if (wb_pending) { 364 drm_writeback_signal_completion(&out->wb_connector, 0); 365 spin_lock_irq(&out->composer_lock); 366 crtc_state->wb_pending = false; 367 spin_unlock_irq(&out->composer_lock); 368 } 369 370 /* 371 * The worker can fall behind the vblank hrtimer, make sure we catch up. 372 */ 373 while (frame_start <= frame_end) 374 drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); 375 } 376 377 static const char * const pipe_crc_sources[] = {"auto"}; 378 379 const char *const *vkms_get_crc_sources(struct drm_crtc *crtc, 380 size_t *count) 381 { 382 *count = ARRAY_SIZE(pipe_crc_sources); 383 return pipe_crc_sources; 384 } 385 386 static int vkms_crc_parse_source(const char *src_name, bool *enabled) 387 { 388 int ret = 0; 389 390 if (!src_name) { 391 *enabled = false; 392 } else if (strcmp(src_name, "auto") == 0) { 393 *enabled = true; 394 } else { 395 *enabled = false; 396 ret = -EINVAL; 397 } 398 399 return ret; 400 } 401 402 int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name, 403 size_t *values_cnt) 404 { 405 bool enabled; 406 407 if (vkms_crc_parse_source(src_name, &enabled) < 0) { 408 DRM_DEBUG_DRIVER("unknown source %s\n", src_name); 409 return -EINVAL; 410 } 411 412 *values_cnt = 1; 413 414 return 0; 415 } 416 417 void vkms_set_composer(struct vkms_output *out, bool enabled) 418 { 419 bool old_enabled; 420 421 if (enabled) 422 drm_crtc_vblank_get(&out->crtc); 423 424 spin_lock_irq(&out->lock); 425 old_enabled = out->composer_enabled; 426 out->composer_enabled = enabled; 427 spin_unlock_irq(&out->lock); 428 429 if (old_enabled) 430 drm_crtc_vblank_put(&out->crtc); 431 } 432 433 int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name) 434 { 435 struct vkms_output *out = drm_crtc_to_vkms_output(crtc); 436 bool enabled = false; 437 int ret = 0; 438 439 ret = vkms_crc_parse_source(src_name, &enabled); 440 441 vkms_set_composer(out, enabled); 442 443 return ret; 444 } 445