xref: /linux/drivers/gpu/drm/nouveau/dispnv50/crc.c (revision 1e5b3968a57d7894d5f86a2ecb58fa057cb6f7b2)
1 // SPDX-License-Identifier: MIT
2 #include <linux/string.h>
3 #include <drm/drm_crtc.h>
4 #include <drm/drm_atomic_helper.h>
5 #include <drm/drm_vblank.h>
6 #include <drm/drm_vblank_work.h>
7 
8 #include <nvif/class.h>
9 #include <nvif/cl0002.h>
10 #include <nvif/timer.h>
11 
12 #include <nvhw/class/cl907d.h>
13 
14 #include "nouveau_drv.h"
15 #include "core.h"
16 #include "head.h"
17 #include "wndw.h"
18 #include "handles.h"
19 #include "crc.h"
20 
21 static const char * const nv50_crc_sources[] = {
22 	[NV50_CRC_SOURCE_NONE] = "none",
23 	[NV50_CRC_SOURCE_AUTO] = "auto",
24 	[NV50_CRC_SOURCE_RG] = "rg",
25 	[NV50_CRC_SOURCE_OUTP_ACTIVE] = "outp-active",
26 	[NV50_CRC_SOURCE_OUTP_COMPLETE] = "outp-complete",
27 	[NV50_CRC_SOURCE_OUTP_INACTIVE] = "outp-inactive",
28 };
29 
30 static int nv50_crc_parse_source(const char *buf, enum nv50_crc_source *s)
31 {
32 	int i;
33 
34 	if (!buf) {
35 		*s = NV50_CRC_SOURCE_NONE;
36 		return 0;
37 	}
38 
39 	i = match_string(nv50_crc_sources, ARRAY_SIZE(nv50_crc_sources), buf);
40 	if (i < 0)
41 		return i;
42 
43 	*s = i;
44 	return 0;
45 }
46 
47 int
48 nv50_crc_verify_source(struct drm_crtc *crtc, const char *source_name,
49 		       size_t *values_cnt)
50 {
51 	struct nouveau_drm *drm = nouveau_drm(crtc->dev);
52 	enum nv50_crc_source source;
53 
54 	if (nv50_crc_parse_source(source_name, &source) < 0) {
55 		NV_DEBUG(drm, "unknown source %s\n", source_name);
56 		return -EINVAL;
57 	}
58 
59 	*values_cnt = 1;
60 	return 0;
61 }
62 
63 const char *const *nv50_crc_get_sources(struct drm_crtc *crtc, size_t *count)
64 {
65 	*count = ARRAY_SIZE(nv50_crc_sources);
66 	return nv50_crc_sources;
67 }
68 
69 static void
70 nv50_crc_program_ctx(struct nv50_head *head,
71 		     struct nv50_crc_notifier_ctx *ctx)
72 {
73 	struct nv50_disp *disp = nv50_disp(head->base.base.dev);
74 	struct nv50_core *core = disp->core;
75 	u32 interlock[NV50_DISP_INTERLOCK__SIZE] = { 0 };
76 
77 	core->func->crc->set_ctx(head, ctx);
78 	core->func->update(core, interlock, false);
79 }
80 
81 static void nv50_crc_ctx_flip_work(struct kthread_work *base)
82 {
83 	struct drm_vblank_work *work = to_drm_vblank_work(base);
84 	struct nv50_crc *crc = container_of(work, struct nv50_crc, flip_work);
85 	struct nv50_head *head = container_of(crc, struct nv50_head, crc);
86 	struct drm_crtc *crtc = &head->base.base;
87 	struct drm_device *dev = crtc->dev;
88 	struct nv50_disp *disp = nv50_disp(dev);
89 	const uint64_t start_vbl = drm_crtc_vblank_count(crtc);
90 	uint64_t end_vbl;
91 	u8 new_idx = crc->ctx_idx ^ 1;
92 
93 	/*
94 	 * We don't want to accidentally wait for longer then the vblank, so
95 	 * try again for the next vblank if we don't grab the lock
96 	 */
97 	if (!mutex_trylock(&disp->mutex)) {
98 		drm_dbg_kms(dev, "Lock contended, delaying CRC ctx flip for %s\n", crtc->name);
99 		drm_vblank_work_schedule(work, start_vbl + 1, true);
100 		return;
101 	}
102 
103 	drm_dbg_kms(dev, "Flipping notifier ctx for %s (%d -> %d)\n",
104 		    crtc->name, crc->ctx_idx, new_idx);
105 
106 	nv50_crc_program_ctx(head, NULL);
107 	nv50_crc_program_ctx(head, &crc->ctx[new_idx]);
108 	mutex_unlock(&disp->mutex);
109 
110 	end_vbl = drm_crtc_vblank_count(crtc);
111 	if (unlikely(end_vbl != start_vbl))
112 		NV_ERROR(nouveau_drm(dev),
113 			 "Failed to flip CRC context on %s on time (%llu > %llu)\n",
114 			 crtc->name, end_vbl, start_vbl);
115 
116 	spin_lock_irq(&crc->lock);
117 	crc->ctx_changed = true;
118 	spin_unlock_irq(&crc->lock);
119 }
120 
121 static inline void nv50_crc_reset_ctx(struct nv50_crc_notifier_ctx *ctx)
122 {
123 	memset_io(ctx->mem.object.map.ptr, 0, ctx->mem.object.map.size);
124 }
125 
126 static void
127 nv50_crc_get_entries(struct nv50_head *head,
128 		     const struct nv50_crc_func *func,
129 		     enum nv50_crc_source source)
130 {
131 	struct drm_crtc *crtc = &head->base.base;
132 	struct nv50_crc *crc = &head->crc;
133 	u32 output_crc;
134 
135 	while (crc->entry_idx < func->num_entries) {
136 		/*
137 		 * While Nvidia's documentation says CRCs are written on each
138 		 * subsequent vblank after being enabled, in practice they
139 		 * aren't written immediately.
140 		 */
141 		output_crc = func->get_entry(head, &crc->ctx[crc->ctx_idx],
142 					     source, crc->entry_idx);
143 		if (!output_crc)
144 			return;
145 
146 		drm_crtc_add_crc_entry(crtc, true, crc->frame, &output_crc);
147 		crc->frame++;
148 		crc->entry_idx++;
149 	}
150 }
151 
152 void nv50_crc_handle_vblank(struct nv50_head *head)
153 {
154 	struct drm_crtc *crtc = &head->base.base;
155 	struct nv50_crc *crc = &head->crc;
156 	const struct nv50_crc_func *func =
157 		nv50_disp(head->base.base.dev)->core->func->crc;
158 	struct nv50_crc_notifier_ctx *ctx;
159 	bool need_reschedule = false;
160 
161 	if (!func)
162 		return;
163 
164 	/*
165 	 * We don't lose events if we aren't able to report CRCs until the
166 	 * next vblank, so only report CRCs if the locks we need aren't
167 	 * contended to prevent missing an actual vblank event
168 	 */
169 	if (!spin_trylock(&crc->lock))
170 		return;
171 
172 	if (!crc->src)
173 		goto out;
174 
175 	ctx = &crc->ctx[crc->ctx_idx];
176 	if (crc->ctx_changed && func->ctx_finished(head, ctx)) {
177 		nv50_crc_get_entries(head, func, crc->src);
178 
179 		crc->ctx_idx ^= 1;
180 		crc->entry_idx = 0;
181 		crc->ctx_changed = false;
182 
183 		/*
184 		 * Unfortunately when notifier contexts are changed during CRC
185 		 * capture, we will inevitably lose the CRC entry for the
186 		 * frame where the hardware actually latched onto the first
187 		 * UPDATE. According to Nvidia's hardware engineers, there's
188 		 * no workaround for this.
189 		 *
190 		 * Now, we could try to be smart here and calculate the number
191 		 * of missed CRCs based on audit timestamps, but those were
192 		 * removed starting with volta. Since we always flush our
193 		 * updates back-to-back without waiting, we'll just be
194 		 * optimistic and assume we always miss exactly one frame.
195 		 */
196 		drm_dbg_kms(head->base.base.dev,
197 			    "Notifier ctx flip for head-%d finished, lost CRC for frame %llu\n",
198 			    head->base.index, crc->frame);
199 		crc->frame++;
200 
201 		nv50_crc_reset_ctx(ctx);
202 		need_reschedule = true;
203 	}
204 
205 	nv50_crc_get_entries(head, func, crc->src);
206 
207 	if (need_reschedule)
208 		drm_vblank_work_schedule(&crc->flip_work,
209 					 drm_crtc_vblank_count(crtc)
210 					 + crc->flip_threshold
211 					 - crc->entry_idx,
212 					 true);
213 
214 out:
215 	spin_unlock(&crc->lock);
216 }
217 
218 static void nv50_crc_wait_ctx_finished(struct nv50_head *head,
219 				       const struct nv50_crc_func *func,
220 				       struct nv50_crc_notifier_ctx *ctx)
221 {
222 	struct drm_device *dev = head->base.base.dev;
223 	struct nouveau_drm *drm = nouveau_drm(dev);
224 	s64 ret;
225 
226 	ret = nvif_msec(&drm->client.device, 50,
227 			if (func->ctx_finished(head, ctx)) break;);
228 	if (ret == -ETIMEDOUT)
229 		NV_ERROR(drm,
230 			 "CRC notifier ctx for head %d not finished after 50ms\n",
231 			 head->base.index);
232 	else if (ret)
233 		NV_ATOMIC(drm,
234 			  "CRC notifier ctx for head-%d finished after %lldns\n",
235 			  head->base.index, ret);
236 }
237 
238 void nv50_crc_atomic_stop_reporting(struct drm_atomic_state *state)
239 {
240 	struct drm_crtc_state *crtc_state;
241 	struct drm_crtc *crtc;
242 	int i;
243 
244 	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
245 		struct nv50_head *head = nv50_head(crtc);
246 		struct nv50_head_atom *asyh = nv50_head_atom(crtc_state);
247 		struct nv50_crc *crc = &head->crc;
248 
249 		if (!asyh->clr.crc)
250 			continue;
251 
252 		spin_lock_irq(&crc->lock);
253 		crc->src = NV50_CRC_SOURCE_NONE;
254 		spin_unlock_irq(&crc->lock);
255 
256 		drm_crtc_vblank_put(crtc);
257 		drm_vblank_work_cancel_sync(&crc->flip_work);
258 
259 		NV_ATOMIC(nouveau_drm(crtc->dev),
260 			  "CRC reporting on vblank for head-%d disabled\n",
261 			  head->base.index);
262 
263 		/* CRC generation is still enabled in hw, we'll just report
264 		 * any remaining CRC entries ourselves after it gets disabled
265 		 * in hardware
266 		 */
267 	}
268 }
269 
270 void nv50_crc_atomic_init_notifier_contexts(struct drm_atomic_state *state)
271 {
272 	struct drm_crtc_state *new_crtc_state;
273 	struct drm_crtc *crtc;
274 	int i;
275 
276 	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
277 		struct nv50_head *head = nv50_head(crtc);
278 		struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state);
279 		struct nv50_crc *crc = &head->crc;
280 		int i;
281 
282 		if (!asyh->set.crc)
283 			continue;
284 
285 		crc->entry_idx = 0;
286 		crc->ctx_changed = false;
287 		for (i = 0; i < ARRAY_SIZE(crc->ctx); i++)
288 			nv50_crc_reset_ctx(&crc->ctx[i]);
289 	}
290 }
291 
292 void nv50_crc_atomic_release_notifier_contexts(struct drm_atomic_state *state)
293 {
294 	const struct nv50_crc_func *func =
295 		nv50_disp(state->dev)->core->func->crc;
296 	struct drm_crtc_state *new_crtc_state;
297 	struct drm_crtc *crtc;
298 	int i;
299 
300 	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
301 		struct nv50_head *head = nv50_head(crtc);
302 		struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state);
303 		struct nv50_crc *crc = &head->crc;
304 		struct nv50_crc_notifier_ctx *ctx = &crc->ctx[crc->ctx_idx];
305 
306 		if (!asyh->clr.crc)
307 			continue;
308 
309 		if (crc->ctx_changed) {
310 			nv50_crc_wait_ctx_finished(head, func, ctx);
311 			ctx = &crc->ctx[crc->ctx_idx ^ 1];
312 		}
313 		nv50_crc_wait_ctx_finished(head, func, ctx);
314 	}
315 }
316 
317 void nv50_crc_atomic_start_reporting(struct drm_atomic_state *state)
318 {
319 	struct drm_crtc_state *crtc_state;
320 	struct drm_crtc *crtc;
321 	int i;
322 
323 	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
324 		struct nv50_head *head = nv50_head(crtc);
325 		struct nv50_head_atom *asyh = nv50_head_atom(crtc_state);
326 		struct nv50_crc *crc = &head->crc;
327 		u64 vbl_count;
328 
329 		if (!asyh->set.crc)
330 			continue;
331 
332 		drm_crtc_vblank_get(crtc);
333 
334 		spin_lock_irq(&crc->lock);
335 		vbl_count = drm_crtc_vblank_count(crtc);
336 		crc->frame = vbl_count;
337 		crc->src = asyh->crc.src;
338 		drm_vblank_work_schedule(&crc->flip_work,
339 					 vbl_count + crc->flip_threshold,
340 					 true);
341 		spin_unlock_irq(&crc->lock);
342 
343 		NV_ATOMIC(nouveau_drm(crtc->dev),
344 			  "CRC reporting on vblank for head-%d enabled\n",
345 			  head->base.index);
346 	}
347 }
348 
349 int nv50_crc_atomic_check_head(struct nv50_head *head,
350 			       struct nv50_head_atom *asyh,
351 			       struct nv50_head_atom *armh)
352 {
353 	struct nv50_atom *atom = nv50_atom(asyh->state.state);
354 	bool changed = armh->crc.src != asyh->crc.src;
355 
356 	if (!armh->crc.src && !asyh->crc.src) {
357 		asyh->set.crc = false;
358 		asyh->clr.crc = false;
359 		return 0;
360 	}
361 
362 	if (drm_atomic_crtc_needs_modeset(&asyh->state) || changed) {
363 		asyh->clr.crc = armh->crc.src && armh->state.active;
364 		asyh->set.crc = asyh->crc.src && asyh->state.active;
365 		if (changed)
366 			asyh->set.or |= armh->or.crc_raster !=
367 					asyh->or.crc_raster;
368 
369 		if (asyh->clr.crc && asyh->set.crc)
370 			atom->flush_disable = true;
371 	} else {
372 		asyh->set.crc = false;
373 		asyh->clr.crc = false;
374 	}
375 
376 	return 0;
377 }
378 
379 void nv50_crc_atomic_check_outp(struct nv50_atom *atom)
380 {
381 	struct drm_crtc *crtc;
382 	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
383 	int i;
384 
385 	if (atom->flush_disable)
386 		return;
387 
388 	for_each_oldnew_crtc_in_state(&atom->state, crtc, old_crtc_state,
389 				      new_crtc_state, i) {
390 		struct nv50_head_atom *armh = nv50_head_atom(old_crtc_state);
391 		struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state);
392 		struct nv50_outp_atom *outp_atom;
393 		struct nouveau_encoder *outp;
394 		struct drm_encoder *encoder, *enc;
395 
396 		enc = nv50_head_atom_get_encoder(armh);
397 		if (!enc)
398 			continue;
399 
400 		outp = nv50_real_outp(enc);
401 		if (!outp)
402 			continue;
403 
404 		encoder = &outp->base.base;
405 
406 		if (!asyh->clr.crc)
407 			continue;
408 
409 		/*
410 		 * Re-programming ORs can't be done in the same flush as
411 		 * disabling CRCs
412 		 */
413 		list_for_each_entry(outp_atom, &atom->outp, head) {
414 			if (outp_atom->encoder == encoder) {
415 				if (outp_atom->set.mask) {
416 					atom->flush_disable = true;
417 					return;
418 				} else {
419 					break;
420 				}
421 			}
422 		}
423 	}
424 }
425 
426 static enum nv50_crc_source_type
427 nv50_crc_source_type(struct nouveau_encoder *outp,
428 		     enum nv50_crc_source source)
429 {
430 	struct dcb_output *dcbe = outp->dcb;
431 
432 	switch (source) {
433 	case NV50_CRC_SOURCE_NONE: return NV50_CRC_SOURCE_TYPE_NONE;
434 	case NV50_CRC_SOURCE_RG:   return NV50_CRC_SOURCE_TYPE_RG;
435 	default:		   break;
436 	}
437 
438 	if (dcbe->location != DCB_LOC_ON_CHIP)
439 		return NV50_CRC_SOURCE_TYPE_PIOR;
440 
441 	switch (dcbe->type) {
442 	case DCB_OUTPUT_DP:	return NV50_CRC_SOURCE_TYPE_SF;
443 	case DCB_OUTPUT_ANALOG:	return NV50_CRC_SOURCE_TYPE_DAC;
444 	default:		return NV50_CRC_SOURCE_TYPE_SOR;
445 	}
446 }
447 
448 void nv50_crc_atomic_set(struct nv50_head *head,
449 			 struct nv50_head_atom *asyh)
450 {
451 	struct drm_crtc *crtc = &head->base.base;
452 	struct drm_device *dev = crtc->dev;
453 	struct nv50_crc *crc = &head->crc;
454 	const struct nv50_crc_func *func = nv50_disp(dev)->core->func->crc;
455 	struct nouveau_encoder *outp;
456 	struct drm_encoder *encoder;
457 
458 	encoder = nv50_head_atom_get_encoder(asyh);
459 	if (!encoder)
460 		return;
461 
462 	outp = nv50_real_outp(encoder);
463 	if (!outp)
464 		return;
465 
466 	func->set_src(head, outp->outp.or.id, nv50_crc_source_type(outp, asyh->crc.src),
467 		      &crc->ctx[crc->ctx_idx]);
468 }
469 
470 void nv50_crc_atomic_clr(struct nv50_head *head)
471 {
472 	const struct nv50_crc_func *func =
473 		nv50_disp(head->base.base.dev)->core->func->crc;
474 
475 	func->set_src(head, 0, NV50_CRC_SOURCE_TYPE_NONE, NULL);
476 }
477 
478 static inline int
479 nv50_crc_raster_type(enum nv50_crc_source source)
480 {
481 	switch (source) {
482 	case NV50_CRC_SOURCE_NONE:
483 	case NV50_CRC_SOURCE_AUTO:
484 	case NV50_CRC_SOURCE_RG:
485 	case NV50_CRC_SOURCE_OUTP_ACTIVE:
486 		return NV907D_HEAD_SET_CONTROL_OUTPUT_RESOURCE_CRC_MODE_ACTIVE_RASTER;
487 	case NV50_CRC_SOURCE_OUTP_COMPLETE:
488 		return NV907D_HEAD_SET_CONTROL_OUTPUT_RESOURCE_CRC_MODE_COMPLETE_RASTER;
489 	case NV50_CRC_SOURCE_OUTP_INACTIVE:
490 		return NV907D_HEAD_SET_CONTROL_OUTPUT_RESOURCE_CRC_MODE_NON_ACTIVE_RASTER;
491 	}
492 
493 	return 0;
494 }
495 
496 /* We handle mapping the memory for CRC notifiers ourselves, since each
497  * notifier needs it's own handle
498  */
499 static inline int
500 nv50_crc_ctx_init(struct nv50_head *head, struct nvif_mmu *mmu,
501 		  struct nv50_crc_notifier_ctx *ctx, size_t len, int idx)
502 {
503 	struct nv50_core *core = nv50_disp(head->base.base.dev)->core;
504 	int ret;
505 
506 	ret = nvif_mem_ctor_map(mmu, "kmsCrcNtfy", NVIF_MEM_VRAM, len, &ctx->mem);
507 	if (ret)
508 		return ret;
509 
510 	ret = nvif_object_ctor(&core->chan.base.user, "kmsCrcNtfyCtxDma",
511 			       NV50_DISP_HANDLE_CRC_CTX(head, idx),
512 			       NV_DMA_IN_MEMORY,
513 			       &(struct nv_dma_v0) {
514 					.target = NV_DMA_V0_TARGET_VRAM,
515 					.access = NV_DMA_V0_ACCESS_RDWR,
516 					.start = ctx->mem.addr,
517 					.limit =  ctx->mem.addr
518 						+ ctx->mem.size - 1,
519 			       }, sizeof(struct nv_dma_v0),
520 			       &ctx->ntfy);
521 	if (ret)
522 		goto fail_fini;
523 
524 	return 0;
525 
526 fail_fini:
527 	nvif_mem_dtor(&ctx->mem);
528 	return ret;
529 }
530 
531 static inline void
532 nv50_crc_ctx_fini(struct nv50_crc_notifier_ctx *ctx)
533 {
534 	nvif_object_dtor(&ctx->ntfy);
535 	nvif_mem_dtor(&ctx->mem);
536 }
537 
538 int nv50_crc_set_source(struct drm_crtc *crtc, const char *source_str)
539 {
540 	struct drm_device *dev = crtc->dev;
541 	struct drm_atomic_state *state;
542 	struct drm_modeset_acquire_ctx ctx;
543 	struct nv50_head *head = nv50_head(crtc);
544 	struct nv50_crc *crc = &head->crc;
545 	const struct nv50_crc_func *func = nv50_disp(dev)->core->func->crc;
546 	struct nvif_mmu *mmu = &nouveau_drm(dev)->client.mmu;
547 	struct nv50_head_atom *asyh;
548 	struct drm_crtc_state *crtc_state;
549 	enum nv50_crc_source source;
550 	int ret = 0, ctx_flags = 0, i;
551 
552 	ret = nv50_crc_parse_source(source_str, &source);
553 	if (ret)
554 		return ret;
555 
556 	/*
557 	 * Since we don't want the user to accidentally interrupt us as we're
558 	 * disabling CRCs
559 	 */
560 	if (source)
561 		ctx_flags |= DRM_MODESET_ACQUIRE_INTERRUPTIBLE;
562 	drm_modeset_acquire_init(&ctx, ctx_flags);
563 
564 	state = drm_atomic_state_alloc(dev);
565 	if (!state) {
566 		ret = -ENOMEM;
567 		goto out_acquire_fini;
568 	}
569 	state->acquire_ctx = &ctx;
570 
571 	if (source) {
572 		for (i = 0; i < ARRAY_SIZE(head->crc.ctx); i++) {
573 			ret = nv50_crc_ctx_init(head, mmu, &crc->ctx[i],
574 						func->notifier_len, i);
575 			if (ret)
576 				goto out_ctx_fini;
577 		}
578 	}
579 
580 retry:
581 	crtc_state = drm_atomic_get_crtc_state(state, &head->base.base);
582 	if (IS_ERR(crtc_state)) {
583 		ret = PTR_ERR(crtc_state);
584 		if (ret == -EDEADLK)
585 			goto deadlock;
586 		else if (ret)
587 			goto out_drop_locks;
588 	}
589 	asyh = nv50_head_atom(crtc_state);
590 	asyh->crc.src = source;
591 	asyh->or.crc_raster = nv50_crc_raster_type(source);
592 
593 	ret = drm_atomic_commit(state);
594 	if (ret == -EDEADLK)
595 		goto deadlock;
596 	else if (ret)
597 		goto out_drop_locks;
598 
599 	if (!source) {
600 		/*
601 		 * If the user specified a custom flip threshold through
602 		 * debugfs, reset it
603 		 */
604 		crc->flip_threshold = func->flip_threshold;
605 	}
606 
607 out_drop_locks:
608 	drm_modeset_drop_locks(&ctx);
609 out_ctx_fini:
610 	if (!source || ret) {
611 		for (i = 0; i < ARRAY_SIZE(crc->ctx); i++)
612 			nv50_crc_ctx_fini(&crc->ctx[i]);
613 	}
614 	drm_atomic_state_put(state);
615 out_acquire_fini:
616 	drm_modeset_acquire_fini(&ctx);
617 	return ret;
618 
619 deadlock:
620 	drm_atomic_state_clear(state);
621 	drm_modeset_backoff(&ctx);
622 	goto retry;
623 }
624 
625 static int
626 nv50_crc_debugfs_flip_threshold_get(struct seq_file *m, void *data)
627 {
628 	struct nv50_head *head = m->private;
629 	struct drm_crtc *crtc = &head->base.base;
630 	struct nv50_crc *crc = &head->crc;
631 	int ret;
632 
633 	ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
634 	if (ret)
635 		return ret;
636 
637 	seq_printf(m, "%d\n", crc->flip_threshold);
638 
639 	drm_modeset_unlock(&crtc->mutex);
640 	return ret;
641 }
642 
643 static int
644 nv50_crc_debugfs_flip_threshold_open(struct inode *inode, struct file *file)
645 {
646 	return single_open(file, nv50_crc_debugfs_flip_threshold_get,
647 			   inode->i_private);
648 }
649 
650 static ssize_t
651 nv50_crc_debugfs_flip_threshold_set(struct file *file,
652 				    const char __user *ubuf, size_t len,
653 				    loff_t *offp)
654 {
655 	struct seq_file *m = file->private_data;
656 	struct nv50_head *head = m->private;
657 	struct nv50_head_atom *armh;
658 	struct drm_crtc *crtc = &head->base.base;
659 	struct nouveau_drm *drm = nouveau_drm(crtc->dev);
660 	struct nv50_crc *crc = &head->crc;
661 	const struct nv50_crc_func *func =
662 		nv50_disp(crtc->dev)->core->func->crc;
663 	int value, ret;
664 
665 	ret = kstrtoint_from_user(ubuf, len, 10, &value);
666 	if (ret)
667 		return ret;
668 
669 	if (value > func->flip_threshold)
670 		return -EINVAL;
671 	else if (value == -1)
672 		value = func->flip_threshold;
673 	else if (value < -1)
674 		return -EINVAL;
675 
676 	ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
677 	if (ret)
678 		return ret;
679 
680 	armh = nv50_head_atom(crtc->state);
681 	if (armh->crc.src) {
682 		ret = -EBUSY;
683 		goto out;
684 	}
685 
686 	NV_DEBUG(drm,
687 		 "Changing CRC flip threshold for next capture on head-%d to %d\n",
688 		 head->base.index, value);
689 	crc->flip_threshold = value;
690 	ret = len;
691 
692 out:
693 	drm_modeset_unlock(&crtc->mutex);
694 	return ret;
695 }
696 
697 static const struct file_operations nv50_crc_flip_threshold_fops = {
698 	.owner = THIS_MODULE,
699 	.open = nv50_crc_debugfs_flip_threshold_open,
700 	.read = seq_read,
701 	.write = nv50_crc_debugfs_flip_threshold_set,
702 	.release = single_release,
703 };
704 
705 int nv50_head_crc_late_register(struct nv50_head *head)
706 {
707 	struct drm_crtc *crtc = &head->base.base;
708 	const struct nv50_crc_func *func =
709 		nv50_disp(crtc->dev)->core->func->crc;
710 	struct dentry *root;
711 
712 	if (!func || !crtc->debugfs_entry)
713 		return 0;
714 
715 	root = debugfs_create_dir("nv_crc", crtc->debugfs_entry);
716 	debugfs_create_file("flip_threshold", 0644, root, head,
717 			    &nv50_crc_flip_threshold_fops);
718 
719 	return 0;
720 }
721 
722 static inline void
723 nv50_crc_init_head(struct nv50_disp *disp, const struct nv50_crc_func *func,
724 		   struct nv50_head *head)
725 {
726 	struct nv50_crc *crc = &head->crc;
727 
728 	crc->flip_threshold = func->flip_threshold;
729 	spin_lock_init(&crc->lock);
730 	drm_vblank_work_init(&crc->flip_work, &head->base.base,
731 			     nv50_crc_ctx_flip_work);
732 }
733 
734 void nv50_crc_init(struct drm_device *dev)
735 {
736 	struct nv50_disp *disp = nv50_disp(dev);
737 	struct drm_crtc *crtc;
738 	const struct nv50_crc_func *func = disp->core->func->crc;
739 
740 	if (!func)
741 		return;
742 
743 	drm_for_each_crtc(crtc, dev)
744 		nv50_crc_init_head(disp, func, nv50_head(crtc));
745 }
746