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_fourcc.h> 8 #include <drm/drm_gem_framebuffer_helper.h> 9 #include <drm/drm_vblank.h> 10 #include <linux/minmax.h> 11 12 #include "vkms_drv.h" 13 14 static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha) 15 { 16 u32 new_color; 17 18 new_color = (src * 0xffff + dst * (0xffff - alpha)); 19 20 return DIV_ROUND_CLOSEST(new_color, 0xffff); 21 } 22 23 /** 24 * pre_mul_alpha_blend - alpha blending equation 25 * @src_frame_info: source framebuffer's metadata 26 * @stage_buffer: The line with the pixels from src_plane 27 * @output_buffer: A line buffer that receives all the blends output 28 * 29 * Using the information from the `frame_info`, this blends only the 30 * necessary pixels from the `stage_buffer` to the `output_buffer` 31 * using premultiplied blend formula. 32 * 33 * The current DRM assumption is that pixel color values have been already 34 * pre-multiplied with the alpha channel values. See more 35 * drm_plane_create_blend_mode_property(). Also, this formula assumes a 36 * completely opaque background. 37 */ 38 static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info, 39 struct line_buffer *stage_buffer, 40 struct line_buffer *output_buffer) 41 { 42 int x_dst = frame_info->dst.x1; 43 struct pixel_argb_u16 *out = output_buffer->pixels + x_dst; 44 struct pixel_argb_u16 *in = stage_buffer->pixels; 45 int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst), 46 stage_buffer->n_pixels); 47 48 for (int x = 0; x < x_limit; x++) { 49 out[x].a = (u16)0xffff; 50 out[x].r = pre_mul_blend_channel(in[x].r, out[x].r, in[x].a); 51 out[x].g = pre_mul_blend_channel(in[x].g, out[x].g, in[x].a); 52 out[x].b = pre_mul_blend_channel(in[x].b, out[x].b, in[x].a); 53 } 54 } 55 56 static bool check_y_limit(struct vkms_frame_info *frame_info, int y) 57 { 58 if (y >= frame_info->dst.y1 && y < frame_info->dst.y2) 59 return true; 60 61 return false; 62 } 63 64 static void fill_background(const struct pixel_argb_u16 *background_color, 65 struct line_buffer *output_buffer) 66 { 67 for (size_t i = 0; i < output_buffer->n_pixels; i++) 68 output_buffer->pixels[i] = *background_color; 69 } 70 71 /** 72 * @wb_frame_info: The writeback frame buffer metadata 73 * @crtc_state: The crtc state 74 * @crc32: The crc output of the final frame 75 * @output_buffer: A buffer of a row that will receive the result of the blend(s) 76 * @stage_buffer: The line with the pixels from plane being blend to the output 77 * 78 * This function blends the pixels (Using the `pre_mul_alpha_blend`) 79 * from all planes, calculates the crc32 of the output from the former step, 80 * and, if necessary, convert and store the output to the writeback buffer. 81 */ 82 static void blend(struct vkms_writeback_job *wb, 83 struct vkms_crtc_state *crtc_state, 84 u32 *crc32, struct line_buffer *stage_buffer, 85 struct line_buffer *output_buffer, size_t row_size) 86 { 87 struct vkms_plane_state **plane = crtc_state->active_planes; 88 u32 n_active_planes = crtc_state->num_active_planes; 89 90 const struct pixel_argb_u16 background_color = { .a = 0xffff }; 91 92 size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay; 93 94 for (size_t y = 0; y < crtc_y_limit; y++) { 95 fill_background(&background_color, output_buffer); 96 97 /* The active planes are composed associatively in z-order. */ 98 for (size_t i = 0; i < n_active_planes; i++) { 99 if (!check_y_limit(plane[i]->frame_info, y)) 100 continue; 101 102 plane[i]->plane_read(stage_buffer, plane[i]->frame_info, y); 103 pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer, 104 output_buffer); 105 } 106 107 *crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size); 108 109 if (wb) 110 wb->wb_write(&wb->wb_frame_info, output_buffer, y); 111 } 112 } 113 114 static int check_format_funcs(struct vkms_crtc_state *crtc_state, 115 struct vkms_writeback_job *active_wb) 116 { 117 struct vkms_plane_state **planes = crtc_state->active_planes; 118 u32 n_active_planes = crtc_state->num_active_planes; 119 120 for (size_t i = 0; i < n_active_planes; i++) 121 if (!planes[i]->plane_read) 122 return -1; 123 124 if (active_wb && !active_wb->wb_write) 125 return -1; 126 127 return 0; 128 } 129 130 static int check_iosys_map(struct vkms_crtc_state *crtc_state) 131 { 132 struct vkms_plane_state **plane_state = crtc_state->active_planes; 133 u32 n_active_planes = crtc_state->num_active_planes; 134 135 for (size_t i = 0; i < n_active_planes; i++) 136 if (iosys_map_is_null(&plane_state[i]->frame_info->map[0])) 137 return -1; 138 139 return 0; 140 } 141 142 static int compose_active_planes(struct vkms_writeback_job *active_wb, 143 struct vkms_crtc_state *crtc_state, 144 u32 *crc32) 145 { 146 size_t line_width, pixel_size = sizeof(struct pixel_argb_u16); 147 struct line_buffer output_buffer, stage_buffer; 148 int ret = 0; 149 150 /* 151 * This check exists so we can call `crc32_le` for the entire line 152 * instead doing it for each channel of each pixel in case 153 * `struct `pixel_argb_u16` had any gap added by the compiler 154 * between the struct fields. 155 */ 156 static_assert(sizeof(struct pixel_argb_u16) == 8); 157 158 if (WARN_ON(check_iosys_map(crtc_state))) 159 return -EINVAL; 160 161 if (WARN_ON(check_format_funcs(crtc_state, active_wb))) 162 return -EINVAL; 163 164 line_width = crtc_state->base.crtc->mode.hdisplay; 165 stage_buffer.n_pixels = line_width; 166 output_buffer.n_pixels = line_width; 167 168 stage_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL); 169 if (!stage_buffer.pixels) { 170 DRM_ERROR("Cannot allocate memory for the output line buffer"); 171 return -ENOMEM; 172 } 173 174 output_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL); 175 if (!output_buffer.pixels) { 176 DRM_ERROR("Cannot allocate memory for intermediate line buffer"); 177 ret = -ENOMEM; 178 goto free_stage_buffer; 179 } 180 181 blend(active_wb, crtc_state, crc32, &stage_buffer, 182 &output_buffer, line_width * pixel_size); 183 184 kvfree(output_buffer.pixels); 185 free_stage_buffer: 186 kvfree(stage_buffer.pixels); 187 188 return ret; 189 } 190 191 /** 192 * vkms_composer_worker - ordered work_struct to compute CRC 193 * 194 * @work: work_struct 195 * 196 * Work handler for composing and computing CRCs. work_struct scheduled in 197 * an ordered workqueue that's periodically scheduled to run by 198 * vkms_vblank_simulate() and flushed at vkms_atomic_commit_tail(). 199 */ 200 void vkms_composer_worker(struct work_struct *work) 201 { 202 struct vkms_crtc_state *crtc_state = container_of(work, 203 struct vkms_crtc_state, 204 composer_work); 205 struct drm_crtc *crtc = crtc_state->base.crtc; 206 struct vkms_writeback_job *active_wb = crtc_state->active_writeback; 207 struct vkms_output *out = drm_crtc_to_vkms_output(crtc); 208 bool crc_pending, wb_pending; 209 u64 frame_start, frame_end; 210 u32 crc32 = 0; 211 int ret; 212 213 spin_lock_irq(&out->composer_lock); 214 frame_start = crtc_state->frame_start; 215 frame_end = crtc_state->frame_end; 216 crc_pending = crtc_state->crc_pending; 217 wb_pending = crtc_state->wb_pending; 218 crtc_state->frame_start = 0; 219 crtc_state->frame_end = 0; 220 crtc_state->crc_pending = false; 221 spin_unlock_irq(&out->composer_lock); 222 223 /* 224 * We raced with the vblank hrtimer and previous work already computed 225 * the crc, nothing to do. 226 */ 227 if (!crc_pending) 228 return; 229 230 if (wb_pending) 231 ret = compose_active_planes(active_wb, crtc_state, &crc32); 232 else 233 ret = compose_active_planes(NULL, crtc_state, &crc32); 234 235 if (ret) 236 return; 237 238 if (wb_pending) { 239 drm_writeback_signal_completion(&out->wb_connector, 0); 240 spin_lock_irq(&out->composer_lock); 241 crtc_state->wb_pending = false; 242 spin_unlock_irq(&out->composer_lock); 243 } 244 245 /* 246 * The worker can fall behind the vblank hrtimer, make sure we catch up. 247 */ 248 while (frame_start <= frame_end) 249 drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); 250 } 251 252 static const char * const pipe_crc_sources[] = {"auto"}; 253 254 const char *const *vkms_get_crc_sources(struct drm_crtc *crtc, 255 size_t *count) 256 { 257 *count = ARRAY_SIZE(pipe_crc_sources); 258 return pipe_crc_sources; 259 } 260 261 static int vkms_crc_parse_source(const char *src_name, bool *enabled) 262 { 263 int ret = 0; 264 265 if (!src_name) { 266 *enabled = false; 267 } else if (strcmp(src_name, "auto") == 0) { 268 *enabled = true; 269 } else { 270 *enabled = false; 271 ret = -EINVAL; 272 } 273 274 return ret; 275 } 276 277 int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name, 278 size_t *values_cnt) 279 { 280 bool enabled; 281 282 if (vkms_crc_parse_source(src_name, &enabled) < 0) { 283 DRM_DEBUG_DRIVER("unknown source %s\n", src_name); 284 return -EINVAL; 285 } 286 287 *values_cnt = 1; 288 289 return 0; 290 } 291 292 void vkms_set_composer(struct vkms_output *out, bool enabled) 293 { 294 bool old_enabled; 295 296 if (enabled) 297 drm_crtc_vblank_get(&out->crtc); 298 299 spin_lock_irq(&out->lock); 300 old_enabled = out->composer_enabled; 301 out->composer_enabled = enabled; 302 spin_unlock_irq(&out->lock); 303 304 if (old_enabled) 305 drm_crtc_vblank_put(&out->crtc); 306 } 307 308 int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name) 309 { 310 struct vkms_output *out = drm_crtc_to_vkms_output(crtc); 311 bool enabled = false; 312 int ret = 0; 313 314 ret = vkms_crc_parse_source(src_name, &enabled); 315 316 vkms_set_composer(out, enabled); 317 318 return ret; 319 } 320