1// SPDX-License-Identifier: MIT
  2/*
  3 * Copyright © 2019 Intel Corporation
  4 */
  5
  6#include <linux/kobject.h>
  7#include <linux/sysfs.h>
  8
  9#include "i915_drv.h"
 10#include "intel_engine.h"
 11#include "intel_engine_heartbeat.h"
 12#include "sysfs_engines.h"
 13
 14struct kobj_engine {
 15	struct kobject base;
 16	struct intel_engine_cs *engine;
 17};
 18
 19static struct intel_engine_cs *kobj_to_engine(struct kobject *kobj)
 20{
 21	return container_of(kobj, struct kobj_engine, base)->engine;
 22}
 23
 24static ssize_t
 25name_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 26{
 27	return sprintf(buf, "%s\n", kobj_to_engine(kobj)->name);
 28}
 29
 30static struct kobj_attribute name_attr =
 31__ATTR(name, 0444, name_show, NULL);
 32
 33static ssize_t
 34class_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 35{
 36	return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_class);
 37}
 38
 39static struct kobj_attribute class_attr =
 40__ATTR(class, 0444, class_show, NULL);
 41
 42static ssize_t
 43inst_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 44{
 45	return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_instance);
 46}
 47
 48static struct kobj_attribute inst_attr =
 49__ATTR(instance, 0444, inst_show, NULL);
 50
 51static ssize_t
 52mmio_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 53{
 54	return sprintf(buf, "0x%x\n", kobj_to_engine(kobj)->mmio_base);
 55}
 56
 57static struct kobj_attribute mmio_attr =
 58__ATTR(mmio_base, 0444, mmio_show, NULL);
 59
 60static const char * const vcs_caps[] = {
 61	[ilog2(I915_VIDEO_CLASS_CAPABILITY_HEVC)] = "hevc",
 62	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
 63};
 64
 65static const char * const vecs_caps[] = {
 66	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
 67};
 68
 69static ssize_t repr_trim(char *buf, ssize_t len)
 70{
 71	/* Trim off the trailing space and replace with a newline */
 72	if (len > PAGE_SIZE)
 73		len = PAGE_SIZE;
 74	if (len > 0)
 75		buf[len - 1] = '\n';
 76
 77	return len;
 78}
 79
 80static ssize_t
 81__caps_show(struct intel_engine_cs *engine,
 82	    u32 caps, char *buf, bool show_unknown)
 83{
 84	const char * const *repr;
 85	int count, n;
 86	ssize_t len;
 87
 88	BUILD_BUG_ON(!typecheck(typeof(caps), engine->uabi_capabilities));
 89
 90	switch (engine->class) {
 91	case VIDEO_DECODE_CLASS:
 92		repr = vcs_caps;
 93		count = ARRAY_SIZE(vcs_caps);
 94		break;
 95
 96	case VIDEO_ENHANCEMENT_CLASS:
 97		repr = vecs_caps;
 98		count = ARRAY_SIZE(vecs_caps);
 99		break;
100
101	default:
102		repr = NULL;
103		count = 0;
104		break;
105	}
106	GEM_BUG_ON(count > BITS_PER_TYPE(typeof(caps)));
107
108	len = 0;
109	for_each_set_bit(n,
110			 (unsigned long *)&caps,
111			 show_unknown ? BITS_PER_TYPE(typeof(caps)) : count) {
112		if (n >= count || !repr[n]) {
113			if (GEM_WARN_ON(show_unknown))
114				len += snprintf(buf + len, PAGE_SIZE - len,
115						"[%x] ", n);
116		} else {
117			len += snprintf(buf + len, PAGE_SIZE - len,
118					"%s ", repr[n]);
119		}
120		if (GEM_WARN_ON(len >= PAGE_SIZE))
121			break;
122	}
123	return repr_trim(buf, len);
124}
125
126static ssize_t
127caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
128{
129	struct intel_engine_cs *engine = kobj_to_engine(kobj);
130
131	return __caps_show(engine, engine->uabi_capabilities, buf, true);
132}
133
134static struct kobj_attribute caps_attr =
135__ATTR(capabilities, 0444, caps_show, NULL);
136
137static ssize_t
138all_caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
139{
140	return __caps_show(kobj_to_engine(kobj), -1, buf, false);
141}
142
143static struct kobj_attribute all_caps_attr =
144__ATTR(known_capabilities, 0444, all_caps_show, NULL);
145
146static ssize_t
147max_spin_store(struct kobject *kobj, struct kobj_attribute *attr,
148	       const char *buf, size_t count)
149{
150	struct intel_engine_cs *engine = kobj_to_engine(kobj);
151	unsigned long long duration;
152	int err;
153
154	/*
155	 * When waiting for a request, if is it currently being executed
156	 * on the GPU, we busywait for a short while before sleeping. The
157	 * premise is that most requests are short, and if it is already
158	 * executing then there is a good chance that it will complete
159	 * before we can setup the interrupt handler and go to sleep.
160	 * We try to offset the cost of going to sleep, by first spinning
161	 * on the request -- if it completed in less time than it would take
162	 * to go sleep, process the interrupt and return back to the client,
163	 * then we have saved the client some latency, albeit at the cost
164	 * of spinning on an expensive CPU core.
165	 *
166	 * While we try to avoid waiting at all for a request that is unlikely
167	 * to complete, deciding how long it is worth spinning is for is an
168	 * arbitrary decision: trading off power vs latency.
169	 */
170
171	err = kstrtoull(buf, 0, &duration);
172	if (err)
173		return err;
174
175	if (duration > jiffies_to_nsecs(2))
176		return -EINVAL;
177
178	WRITE_ONCE(engine->props.max_busywait_duration_ns, duration);
179
180	return count;
181}
182
183static ssize_t
184max_spin_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
185{
186	struct intel_engine_cs *engine = kobj_to_engine(kobj);
187
188	return sprintf(buf, "%lu\n", engine->props.max_busywait_duration_ns);
189}
190
191static struct kobj_attribute max_spin_attr =
192__ATTR(max_busywait_duration_ns, 0644, max_spin_show, max_spin_store);
193
194static ssize_t
195max_spin_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
196{
197	struct intel_engine_cs *engine = kobj_to_engine(kobj);
198
199	return sprintf(buf, "%lu\n", engine->defaults.max_busywait_duration_ns);
200}
201
202static struct kobj_attribute max_spin_def =
203__ATTR(max_busywait_duration_ns, 0444, max_spin_default, NULL);
204
205static ssize_t
206timeslice_store(struct kobject *kobj, struct kobj_attribute *attr,
207		const char *buf, size_t count)
208{
209	struct intel_engine_cs *engine = kobj_to_engine(kobj);
210	unsigned long long duration;
211	int err;
212
213	/*
214	 * Execlists uses a scheduling quantum (a timeslice) to alternate
215	 * execution between ready-to-run contexts of equal priority. This
216	 * ensures that all users (though only if they of equal importance)
217	 * have the opportunity to run and prevents livelocks where contexts
218	 * may have implicit ordering due to userspace semaphores.
219	 */
220
221	err = kstrtoull(buf, 0, &duration);
222	if (err)
223		return err;
224
225	if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
226		return -EINVAL;
227
228	WRITE_ONCE(engine->props.timeslice_duration_ms, duration);
229
230	if (execlists_active(&engine->execlists))
231		set_timer_ms(&engine->execlists.timer, duration);
232
233	return count;
234}
235
236static ssize_t
237timeslice_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
238{
239	struct intel_engine_cs *engine = kobj_to_engine(kobj);
240
241	return sprintf(buf, "%lu\n", engine->props.timeslice_duration_ms);
242}
243
244static struct kobj_attribute timeslice_duration_attr =
245__ATTR(timeslice_duration_ms, 0644, timeslice_show, timeslice_store);
246
247static ssize_t
248timeslice_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
249{
250	struct intel_engine_cs *engine = kobj_to_engine(kobj);
251
252	return sprintf(buf, "%lu\n", engine->defaults.timeslice_duration_ms);
253}
254
255static struct kobj_attribute timeslice_duration_def =
256__ATTR(timeslice_duration_ms, 0444, timeslice_default, NULL);
257
258static ssize_t
259stop_store(struct kobject *kobj, struct kobj_attribute *attr,
260	   const char *buf, size_t count)
261{
262	struct intel_engine_cs *engine = kobj_to_engine(kobj);
263	unsigned long long duration;
264	int err;
265
266	/*
267	 * When we allow ourselves to sleep before a GPU reset after disabling
268	 * submission, even for a few milliseconds, gives an innocent context
269	 * the opportunity to clear the GPU before the reset occurs. However,
270	 * how long to sleep depends on the typical non-preemptible duration
271	 * (a similar problem to determining the ideal preempt-reset timeout
272	 * or even the heartbeat interval).
273	 */
274
275	err = kstrtoull(buf, 0, &duration);
276	if (err)
277		return err;
278
279	if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
280		return -EINVAL;
281
282	WRITE_ONCE(engine->props.stop_timeout_ms, duration);
283	return count;
284}
285
286static ssize_t
287stop_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
288{
289	struct intel_engine_cs *engine = kobj_to_engine(kobj);
290
291	return sprintf(buf, "%lu\n", engine->props.stop_timeout_ms);
292}
293
294static struct kobj_attribute stop_timeout_attr =
295__ATTR(stop_timeout_ms, 0644, stop_show, stop_store);
296
297static ssize_t
298stop_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
299{
300	struct intel_engine_cs *engine = kobj_to_engine(kobj);
301
302	return sprintf(buf, "%lu\n", engine->defaults.stop_timeout_ms);
303}
304
305static struct kobj_attribute stop_timeout_def =
306__ATTR(stop_timeout_ms, 0444, stop_default, NULL);
307
308static ssize_t
309preempt_timeout_store(struct kobject *kobj, struct kobj_attribute *attr,
310		      const char *buf, size_t count)
311{
312	struct intel_engine_cs *engine = kobj_to_engine(kobj);
313	unsigned long long timeout;
314	int err;
315
316	/*
317	 * After initialising a preemption request, we give the current
318	 * resident a small amount of time to vacate the GPU. The preemption
319	 * request is for a higher priority context and should be immediate to
320	 * maintain high quality of service (and avoid priority inversion).
321	 * However, the preemption granularity of the GPU can be quite coarse
322	 * and so we need a compromise.
323	 */
324
325	err = kstrtoull(buf, 0, &timeout);
326	if (err)
327		return err;
328
329	if (timeout > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
330		return -EINVAL;
331
332	WRITE_ONCE(engine->props.preempt_timeout_ms, timeout);
333
334	if (READ_ONCE(engine->execlists.pending[0]))
335		set_timer_ms(&engine->execlists.preempt, timeout);
336
337	return count;
338}
339
340static ssize_t
341preempt_timeout_show(struct kobject *kobj, struct kobj_attribute *attr,
342		     char *buf)
343{
344	struct intel_engine_cs *engine = kobj_to_engine(kobj);
345
346	return sprintf(buf, "%lu\n", engine->props.preempt_timeout_ms);
347}
348
349static struct kobj_attribute preempt_timeout_attr =
350__ATTR(preempt_timeout_ms, 0644, preempt_timeout_show, preempt_timeout_store);
351
352static ssize_t
353preempt_timeout_default(struct kobject *kobj, struct kobj_attribute *attr,
354			char *buf)
355{
356	struct intel_engine_cs *engine = kobj_to_engine(kobj);
357
358	return sprintf(buf, "%lu\n", engine->defaults.preempt_timeout_ms);
359}
360
361static struct kobj_attribute preempt_timeout_def =
362__ATTR(preempt_timeout_ms, 0444, preempt_timeout_default, NULL);
363
364static ssize_t
365heartbeat_store(struct kobject *kobj, struct kobj_attribute *attr,
366		const char *buf, size_t count)
367{
368	struct intel_engine_cs *engine = kobj_to_engine(kobj);
369	unsigned long long delay;
370	int err;
371
372	/*
373	 * We monitor the health of the system via periodic heartbeat pulses.
374	 * The pulses also provide the opportunity to perform garbage
375	 * collection.  However, we interpret an incomplete pulse (a missed
376	 * heartbeat) as an indication that the system is no longer responsive,
377	 * i.e. hung, and perform an engine or full GPU reset. Given that the
378	 * preemption granularity can be very coarse on a system, the optimal
379	 * value for any workload is unknowable!
380	 */
381
382	err = kstrtoull(buf, 0, &delay);
383	if (err)
384		return err;
385
386	if (delay >= jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
387		return -EINVAL;
388
389	err = intel_engine_set_heartbeat(engine, delay);
390	if (err)
391		return err;
392
393	return count;
394}
395
396static ssize_t
397heartbeat_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
398{
399	struct intel_engine_cs *engine = kobj_to_engine(kobj);
400
401	return sprintf(buf, "%lu\n", engine->props.heartbeat_interval_ms);
402}
403
404static struct kobj_attribute heartbeat_interval_attr =
405__ATTR(heartbeat_interval_ms, 0644, heartbeat_show, heartbeat_store);
406
407static ssize_t
408heartbeat_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
409{
410	struct intel_engine_cs *engine = kobj_to_engine(kobj);
411
412	return sprintf(buf, "%lu\n", engine->defaults.heartbeat_interval_ms);
413}
414
415static struct kobj_attribute heartbeat_interval_def =
416__ATTR(heartbeat_interval_ms, 0444, heartbeat_default, NULL);
417
418static void kobj_engine_release(struct kobject *kobj)
419{
420	kfree(kobj);
421}
422
423static struct kobj_type kobj_engine_type = {
424	.release = kobj_engine_release,
425	.sysfs_ops = &kobj_sysfs_ops
426};
427
428static struct kobject *
429kobj_engine(struct kobject *dir, struct intel_engine_cs *engine)
430{
431	struct kobj_engine *ke;
432
433	ke = kzalloc(sizeof(*ke), GFP_KERNEL);
434	if (!ke)
435		return NULL;
436
437	kobject_init(&ke->base, &kobj_engine_type);
438	ke->engine = engine;
439
440	if (kobject_add(&ke->base, dir, "%s", engine->name)) {
441		kobject_put(&ke->base);
442		return NULL;
443	}
444
445	/* xfer ownership to sysfs tree */
446	return &ke->base;
447}
448
449static void add_defaults(struct kobj_engine *parent)
450{
451	static const struct attribute *files[] = {
452		&max_spin_def.attr,
453		&stop_timeout_def.attr,
454#if CONFIG_DRM_I915_HEARTBEAT_INTERVAL
455		&heartbeat_interval_def.attr,
456#endif
457		NULL
458	};
459	struct kobj_engine *ke;
460
461	ke = kzalloc(sizeof(*ke), GFP_KERNEL);
462	if (!ke)
463		return;
464
465	kobject_init(&ke->base, &kobj_engine_type);
466	ke->engine = parent->engine;
467
468	if (kobject_add(&ke->base, &parent->base, "%s", ".defaults")) {
469		kobject_put(&ke->base);
470		return;
471	}
472
473	if (sysfs_create_files(&ke->base, files))
474		return;
475
476	if (intel_engine_has_timeslices(ke->engine) &&
477	    sysfs_create_file(&ke->base, &timeslice_duration_def.attr))
478		return;
479
480	if (intel_engine_has_preempt_reset(ke->engine) &&
481	    sysfs_create_file(&ke->base, &preempt_timeout_def.attr))
482		return;
483}
484
485void intel_engines_add_sysfs(struct drm_i915_private *i915)
486{
487	static const struct attribute *files[] = {
488		&name_attr.attr,
489		&class_attr.attr,
490		&inst_attr.attr,
491		&mmio_attr.attr,
492		&caps_attr.attr,
493		&all_caps_attr.attr,
494		&max_spin_attr.attr,
495		&stop_timeout_attr.attr,
496#if CONFIG_DRM_I915_HEARTBEAT_INTERVAL
497		&heartbeat_interval_attr.attr,
498#endif
499		NULL
500	};
501
502	struct device *kdev = i915->drm.primary->kdev;
503	struct intel_engine_cs *engine;
504	struct kobject *dir;
505
506	dir = kobject_create_and_add("engine", &kdev->kobj);
507	if (!dir)
508		return;
509
510	for_each_uabi_engine(engine, i915) {
511		struct kobject *kobj;
512
513		kobj = kobj_engine(dir, engine);
514		if (!kobj)
515			goto err_engine;
516
517		if (sysfs_create_files(kobj, files))
518			goto err_object;
519
520		if (intel_engine_has_timeslices(engine) &&
521		    sysfs_create_file(kobj, &timeslice_duration_attr.attr))
522			goto err_engine;
523
524		if (intel_engine_has_preempt_reset(engine) &&
525		    sysfs_create_file(kobj, &preempt_timeout_attr.attr))
526			goto err_engine;
527
528		add_defaults(container_of(kobj, struct kobj_engine, base));
529
530		if (0) {
531err_object:
532			kobject_put(kobj);
533err_engine:
534			dev_err(kdev, "Failed to add sysfs engine '%s'\n",
535				engine->name);
536			break;
537		}
538	}
539}