43  * DOC: CRC ABI
45  * DRM device drivers can provide to userspace CRC information of each frame as
46  * it reached a given hardware component (a CRC sampling "source").
49  * file dri/0/crtc-N/crc/control in debugfs, with N being the :ref:`index of
54  * Once frame CRC generation is enabled, userspace can capture them by reading
55  * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
57  * containing the CRC data. Fields are separated by a single space and the number
58  * of CRC fields is source-specific.
60  * Note that though in some cases the CRC is computed in a specified way and on
61  * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
64  * rely on being able to generate matching CRC values for the frame contents that
70  * The debugfs files are automatically set up if those vfuncs are set. CRC samples
75  * CRC results must be reliable across non-full-modeset atomic commits, so if a
77  * CRC generation, then the driver must mark that commit as a full modeset
79  * consistent results, generic userspace must re-setup CRC generation after a
100 				if (strcmp(sources[i], crtc->crc.source))  in crc_control_show()
109 	seq_printf(m, "%s*\n", crtc->crc.source);  in crc_control_show()
125 	struct drm_crtc_crc *crc = &crtc->crc;  in crc_control_write()  local
134 		DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",  in crc_control_write()
152 	spin_lock_irq(&crc->lock);  in crc_control_write()
154 	if (crc->opened) {  in crc_control_write()
155 		spin_unlock_irq(&crc->lock);  in crc_control_write()
160 	kfree(crc->source);  in crc_control_write()
161 	crc->source = source;  in crc_control_write()
163 	spin_unlock_irq(&crc->lock);  in crc_control_write()
178 static int crtc_crc_data_count(struct drm_crtc_crc *crc)  in crtc_crc_data_count()  argument
180 	assert_spin_locked(&crc->lock);  in crtc_crc_data_count()
181 	return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);  in crtc_crc_data_count()
184 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)  in crtc_crc_cleanup()  argument
186 	kfree(crc->entries);  in crtc_crc_cleanup()
187 	crc->overflow = false;  in crtc_crc_cleanup()
188 	crc->entries = NULL;  in crtc_crc_cleanup()
189 	crc->head = 0;  in crtc_crc_cleanup()
190 	crc->tail = 0;  in crtc_crc_cleanup()
191 	crc->values_cnt = 0;  in crtc_crc_cleanup()
192 	crc->opened = false;  in crtc_crc_cleanup()
198 	struct drm_crtc_crc *crc = &crtc->crc;  in crtc_crc_open()  local
216 	ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);  in crtc_crc_open()
230 	spin_lock_irq(&crc->lock);  in crtc_crc_open()
231 	if (!crc->opened) {  in crtc_crc_open()
232 		crc->opened = true;  in crtc_crc_open()
233 		crc->entries = entries;  in crtc_crc_open()
234 		crc->values_cnt = values_cnt;  in crtc_crc_open()
238 	spin_unlock_irq(&crc->lock);  in crtc_crc_open()
245 	ret = crtc->funcs->set_crc_source(crtc, crc->source);  in crtc_crc_open()
252 	spin_lock_irq(&crc->lock);  in crtc_crc_open()
253 	crtc_crc_cleanup(crc);  in crtc_crc_open()
254 	spin_unlock_irq(&crc->lock);  in crtc_crc_open()
261 	struct drm_crtc_crc *crc = &crtc->crc;  in crtc_crc_release()  local
264 	spin_lock_irq(&crc->lock);  in crtc_crc_release()
265 	crc->opened = false;  in crtc_crc_release()
266 	spin_unlock_irq(&crc->lock);  in crtc_crc_release()
270 	spin_lock_irq(&crc->lock);  in crtc_crc_release()
271 	crtc_crc_cleanup(crc);  in crtc_crc_release()
272 	spin_unlock_irq(&crc->lock);  in crtc_crc_release()
278  * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
288 	struct drm_crtc_crc *crc = &crtc->crc;  in crtc_crc_read()  local
293 	spin_lock_irq(&crc->lock);  in crtc_crc_read()
295 	if (!crc->source) {  in crtc_crc_read()
296 		spin_unlock_irq(&crc->lock);  in crtc_crc_read()
301 	while (crtc_crc_data_count(crc) == 0) {  in crtc_crc_read()
303 			spin_unlock_irq(&crc->lock);  in crtc_crc_read()
307 		ret = wait_event_interruptible_lock_irq(crc->wq,  in crtc_crc_read()
308 							crtc_crc_data_count(crc),  in crtc_crc_read()
309 							crc->lock);  in crtc_crc_read()
311 			spin_unlock_irq(&crc->lock);  in crtc_crc_read()
317 	entry = &crc->entries[crc->tail];  in crtc_crc_read()
319 	if (count < LINE_LEN(crc->values_cnt)) {  in crtc_crc_read()
320 		spin_unlock_irq(&crc->lock);  in crtc_crc_read()
325 	crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);  in crtc_crc_read()
327 	spin_unlock_irq(&crc->lock);  in crtc_crc_read()
334 	for (i = 0; i < crc->values_cnt; i++)  in crtc_crc_read()
336 	sprintf(buf + 10 + crc->values_cnt * 11, "\n");  in crtc_crc_read()
338 	if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))  in crtc_crc_read()
341 	return LINE_LEN(crc->values_cnt);  in crtc_crc_read()
347 	struct drm_crtc_crc *crc = &crtc->crc;  in crtc_crc_poll()  local
350 	poll_wait(file, &crc->wq, wait);  in crtc_crc_poll()
352 	spin_lock_irq(&crc->lock);  in crtc_crc_poll()
353 	if (crc->source && crtc_crc_data_count(crc))  in crtc_crc_poll()
355 	spin_unlock_irq(&crc->lock);  in crtc_crc_poll()
375 	crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);  in drm_debugfs_crtc_crc_add()
384  * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
388  * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
396 	struct drm_crtc_crc *crc = &crtc->crc;  in drm_crtc_add_crc_entry()  local
401 	spin_lock_irqsave(&crc->lock, flags);  in drm_crtc_add_crc_entry()
404 	if (!crc->entries) {  in drm_crtc_add_crc_entry()
405 		spin_unlock_irqrestore(&crc->lock, flags);  in drm_crtc_add_crc_entry()
409 	head = crc->head;  in drm_crtc_add_crc_entry()
410 	tail = crc->tail;  in drm_crtc_add_crc_entry()
413 		bool was_overflow = crc->overflow;  in drm_crtc_add_crc_entry()
415 		crc->overflow = true;  in drm_crtc_add_crc_entry()
416 		spin_unlock_irqrestore(&crc->lock, flags);  in drm_crtc_add_crc_entry()
419 			DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");  in drm_crtc_add_crc_entry()
424 	entry = &crc->entries[head];  in drm_crtc_add_crc_entry()
427 	memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);  in drm_crtc_add_crc_entry()
430 	crc->head = head;  in drm_crtc_add_crc_entry()
432 	spin_unlock_irqrestore(&crc->lock, flags);  in drm_crtc_add_crc_entry()
434 	wake_up_interruptible(&crc->wq);  in drm_crtc_add_crc_entry()