sysfs_engines.c

  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 "i915_timer_util.h"
 11#include "intel_engine.h"
 12#include "intel_engine_heartbeat.h"
 13#include "sysfs_engines.h"
 14
 15struct kobj_engine {
 16	struct kobject base;
 17	struct intel_engine_cs *engine;
 18};
 19
 20static struct intel_engine_cs *kobj_to_engine(struct kobject *kobj)
 21{
 22	return container_of(kobj, struct kobj_engine, base)->engine;
 23}
 24
 25static ssize_t
 26name_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 27{
 28	return sysfs_emit(buf, "%s\n", kobj_to_engine(kobj)->name);
 29}
 30
 31static const struct kobj_attribute name_attr =
 32__ATTR(name, 0444, name_show, NULL);
 33
 34static ssize_t
 35class_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 36{
 37	return sysfs_emit(buf, "%d\n", kobj_to_engine(kobj)->uabi_class);
 38}
 39
 40static const struct kobj_attribute class_attr =
 41__ATTR(class, 0444, class_show, NULL);
 42
 43static ssize_t
 44inst_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 45{
 46	return sysfs_emit(buf, "%d\n", kobj_to_engine(kobj)->uabi_instance);
 47}
 48
 49static const struct kobj_attribute inst_attr =
 50__ATTR(instance, 0444, inst_show, NULL);
 51
 52static ssize_t
 53mmio_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 54{
 55	return sysfs_emit(buf, "0x%x\n", kobj_to_engine(kobj)->mmio_base);
 56}
 57
 58static const struct kobj_attribute mmio_attr =
 59__ATTR(mmio_base, 0444, mmio_show, NULL);
 60
 61static const char * const vcs_caps[] = {
 62	[ilog2(I915_VIDEO_CLASS_CAPABILITY_HEVC)] = "hevc",
 63	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
 64};
 65
 66static const char * const vecs_caps[] = {
 67	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
 68};
 69
 70static ssize_t repr_trim(char *buf, ssize_t len)
 71{
 72	/* Trim off the trailing space and replace with a newline */
 73	if (len > PAGE_SIZE)
 74		len = PAGE_SIZE;
 75	if (len > 0)
 76		buf[len - 1] = '\n';
 77
 78	return len;
 79}
 80
 81static ssize_t
 82__caps_show(struct intel_engine_cs *engine,
 83	    unsigned long caps, char *buf, bool show_unknown)
 84{
 85	const char * const *repr;
 86	int count, n;
 87	ssize_t len;
 88
 89	switch (engine->class) {
 90	case VIDEO_DECODE_CLASS:
 91		repr = vcs_caps;
 92		count = ARRAY_SIZE(vcs_caps);
 93		break;
 94
 95	case VIDEO_ENHANCEMENT_CLASS:
 96		repr = vecs_caps;
 97		count = ARRAY_SIZE(vecs_caps);
 98		break;
 99
100	default:
101		repr = NULL;
102		count = 0;
103		break;
104	}
105	GEM_BUG_ON(count > BITS_PER_LONG);
106
107	len = 0;
108	for_each_set_bit(n, &caps, show_unknown ? BITS_PER_LONG : count) {
109		if (n >= count || !repr[n]) {
110			if (GEM_WARN_ON(show_unknown))
111				len += sysfs_emit_at(buf, len, "[%x] ", n);
112		} else {
113			len += sysfs_emit_at(buf, len, "%s ", repr[n]);
114		}
115		if (GEM_WARN_ON(len >= PAGE_SIZE))
116			break;
117	}
118	return repr_trim(buf, len);
119}
120
121static ssize_t
122caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
123{
124	struct intel_engine_cs *engine = kobj_to_engine(kobj);
125
126	return __caps_show(engine, engine->uabi_capabilities, buf, true);
127}
128
129static const struct kobj_attribute caps_attr =
130__ATTR(capabilities, 0444, caps_show, NULL);
131
132static ssize_t
133all_caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
134{
135	return __caps_show(kobj_to_engine(kobj), -1, buf, false);
136}
137
138static const struct kobj_attribute all_caps_attr =
139__ATTR(known_capabilities, 0444, all_caps_show, NULL);
140
141static ssize_t
142max_spin_store(struct kobject *kobj, struct kobj_attribute *attr,
143	       const char *buf, size_t count)
144{
145	struct intel_engine_cs *engine = kobj_to_engine(kobj);
146	unsigned long long duration, clamped;
147	int err;
148
149	/*
150	 * When waiting for a request, if is it currently being executed
151	 * on the GPU, we busywait for a short while before sleeping. The
152	 * premise is that most requests are short, and if it is already
153	 * executing then there is a good chance that it will complete
154	 * before we can setup the interrupt handler and go to sleep.
155	 * We try to offset the cost of going to sleep, by first spinning
156	 * on the request -- if it completed in less time than it would take
157	 * to go sleep, process the interrupt and return back to the client,
158	 * then we have saved the client some latency, albeit at the cost
159	 * of spinning on an expensive CPU core.
160	 *
161	 * While we try to avoid waiting at all for a request that is unlikely
162	 * to complete, deciding how long it is worth spinning is for is an
163	 * arbitrary decision: trading off power vs latency.
164	 */
165
166	err = kstrtoull(buf, 0, &duration);
167	if (err)
168		return err;
169
170	clamped = intel_clamp_max_busywait_duration_ns(engine, duration);
171	if (duration != clamped)
172		return -EINVAL;
173
174	WRITE_ONCE(engine->props.max_busywait_duration_ns, duration);
175
176	return count;
177}
178
179static ssize_t
180max_spin_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
181{
182	struct intel_engine_cs *engine = kobj_to_engine(kobj);
183
184	return sysfs_emit(buf, "%lu\n", engine->props.max_busywait_duration_ns);
185}
186
187static const struct kobj_attribute max_spin_attr =
188__ATTR(max_busywait_duration_ns, 0644, max_spin_show, max_spin_store);
189
190static ssize_t
191max_spin_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
192{
193	struct intel_engine_cs *engine = kobj_to_engine(kobj);
194
195	return sysfs_emit(buf, "%lu\n", engine->defaults.max_busywait_duration_ns);
196}
197
198static const struct kobj_attribute max_spin_def =
199__ATTR(max_busywait_duration_ns, 0444, max_spin_default, NULL);
200
201static ssize_t
202timeslice_store(struct kobject *kobj, struct kobj_attribute *attr,
203		const char *buf, size_t count)
204{
205	struct intel_engine_cs *engine = kobj_to_engine(kobj);
206	unsigned long long duration, clamped;
207	int err;
208
209	/*
210	 * Execlists uses a scheduling quantum (a timeslice) to alternate
211	 * execution between ready-to-run contexts of equal priority. This
212	 * ensures that all users (though only if they of equal importance)
213	 * have the opportunity to run and prevents livelocks where contexts
214	 * may have implicit ordering due to userspace semaphores.
215	 */
216
217	err = kstrtoull(buf, 0, &duration);
218	if (err)
219		return err;
220
221	clamped = intel_clamp_timeslice_duration_ms(engine, duration);
222	if (duration != clamped)
223		return -EINVAL;
224
225	WRITE_ONCE(engine->props.timeslice_duration_ms, duration);
226
227	if (execlists_active(&engine->execlists))
228		set_timer_ms(&engine->execlists.timer, duration);
229
230	return count;
231}
232
233static ssize_t
234timeslice_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
235{
236	struct intel_engine_cs *engine = kobj_to_engine(kobj);
237
238	return sysfs_emit(buf, "%lu\n", engine->props.timeslice_duration_ms);
239}
240
241static const struct kobj_attribute timeslice_duration_attr =
242__ATTR(timeslice_duration_ms, 0644, timeslice_show, timeslice_store);
243
244static ssize_t
245timeslice_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
246{
247	struct intel_engine_cs *engine = kobj_to_engine(kobj);
248
249	return sysfs_emit(buf, "%lu\n", engine->defaults.timeslice_duration_ms);
250}
251
252static const struct kobj_attribute timeslice_duration_def =
253__ATTR(timeslice_duration_ms, 0444, timeslice_default, NULL);
254
255static ssize_t
256stop_store(struct kobject *kobj, struct kobj_attribute *attr,
257	   const char *buf, size_t count)
258{
259	struct intel_engine_cs *engine = kobj_to_engine(kobj);
260	unsigned long long duration, clamped;
261	int err;
262
263	/*
264	 * When we allow ourselves to sleep before a GPU reset after disabling
265	 * submission, even for a few milliseconds, gives an innocent context
266	 * the opportunity to clear the GPU before the reset occurs. However,
267	 * how long to sleep depends on the typical non-preemptible duration
268	 * (a similar problem to determining the ideal preempt-reset timeout
269	 * or even the heartbeat interval).
270	 */
271
272	err = kstrtoull(buf, 0, &duration);
273	if (err)
274		return err;
275
276	clamped = intel_clamp_stop_timeout_ms(engine, duration);
277	if (duration != clamped)
278		return -EINVAL;
279
280	WRITE_ONCE(engine->props.stop_timeout_ms, duration);
281	return count;
282}
283
284static ssize_t
285stop_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
286{
287	struct intel_engine_cs *engine = kobj_to_engine(kobj);
288
289	return sysfs_emit(buf, "%lu\n", engine->props.stop_timeout_ms);
290}
291
292static const struct kobj_attribute stop_timeout_attr =
293__ATTR(stop_timeout_ms, 0644, stop_show, stop_store);
294
295static ssize_t
296stop_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
297{
298	struct intel_engine_cs *engine = kobj_to_engine(kobj);
299
300	return sysfs_emit(buf, "%lu\n", engine->defaults.stop_timeout_ms);
301}
302
303static const struct kobj_attribute stop_timeout_def =
304__ATTR(stop_timeout_ms, 0444, stop_default, NULL);
305
306static ssize_t
307preempt_timeout_store(struct kobject *kobj, struct kobj_attribute *attr,
308		      const char *buf, size_t count)
309{
310	struct intel_engine_cs *engine = kobj_to_engine(kobj);
311	unsigned long long timeout, clamped;
312	int err;
313
314	/*
315	 * After initialising a preemption request, we give the current
316	 * resident a small amount of time to vacate the GPU. The preemption
317	 * request is for a higher priority context and should be immediate to
318	 * maintain high quality of service (and avoid priority inversion).
319	 * However, the preemption granularity of the GPU can be quite coarse
320	 * and so we need a compromise.
321	 */
322
323	err = kstrtoull(buf, 0, &timeout);
324	if (err)
325		return err;
326
327	clamped = intel_clamp_preempt_timeout_ms(engine, timeout);
328	if (timeout != clamped)
329		return -EINVAL;
330
331	WRITE_ONCE(engine->props.preempt_timeout_ms, timeout);
332
333	if (READ_ONCE(engine->execlists.pending[0]))
334		set_timer_ms(&engine->execlists.preempt, timeout);
335
336	return count;
337}
338
339static ssize_t
340preempt_timeout_show(struct kobject *kobj, struct kobj_attribute *attr,
341		     char *buf)
342{
343	struct intel_engine_cs *engine = kobj_to_engine(kobj);
344
345	return sysfs_emit(buf, "%lu\n", engine->props.preempt_timeout_ms);
346}
347
348static const struct kobj_attribute preempt_timeout_attr =
349__ATTR(preempt_timeout_ms, 0644, preempt_timeout_show, preempt_timeout_store);
350
351static ssize_t
352preempt_timeout_default(struct kobject *kobj, struct kobj_attribute *attr,
353			char *buf)
354{
355	struct intel_engine_cs *engine = kobj_to_engine(kobj);
356
357	return sysfs_emit(buf, "%lu\n", engine->defaults.preempt_timeout_ms);
358}
359
360static const struct kobj_attribute preempt_timeout_def =
361__ATTR(preempt_timeout_ms, 0444, preempt_timeout_default, NULL);
362
363static ssize_t
364heartbeat_store(struct kobject *kobj, struct kobj_attribute *attr,
365		const char *buf, size_t count)
366{
367	struct intel_engine_cs *engine = kobj_to_engine(kobj);
368	unsigned long long delay, clamped;
369	int err;
370
371	/*
372	 * We monitor the health of the system via periodic heartbeat pulses.
373	 * The pulses also provide the opportunity to perform garbage
374	 * collection.  However, we interpret an incomplete pulse (a missed
375	 * heartbeat) as an indication that the system is no longer responsive,
376	 * i.e. hung, and perform an engine or full GPU reset. Given that the
377	 * preemption granularity can be very coarse on a system, the optimal
378	 * value for any workload is unknowable!
379	 */
380
381	err = kstrtoull(buf, 0, &delay);
382	if (err)
383		return err;
384
385	clamped = intel_clamp_heartbeat_interval_ms(engine, delay);
386	if (delay != clamped)
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 sysfs_emit(buf, "%lu\n", engine->props.heartbeat_interval_ms);
402}
403
404static const 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 sysfs_emit(buf, "%lu\n", engine->defaults.heartbeat_interval_ms);
413}
414
415static const 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 const 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 * const 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 * const 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_warn(kdev, "Failed to add sysfs engine '%s'\n",
535				 engine->name);
536		}
537	}
538}