1 files changed, 281 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
new file mode 100644
index 000000000..f7b2e07e2
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -0,0 +1,281 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include "i915_drv.h"
+
+#include "intel_breadcrumbs.h"
+#include "intel_context.h"
+#include "intel_engine.h"
+#include "intel_engine_heartbeat.h"
+#include "intel_engine_pm.h"
+#include "intel_gt.h"
+#include "intel_gt_pm.h"
+#include "intel_rc6.h"
+#include "intel_ring.h"
+#include "shmem_utils.h"
+
+static int __engine_unpark(struct intel_wakeref *wf)
+{
+	struct intel_engine_cs *engine =
+		container_of(wf, typeof(*engine), wakeref);
+	struct intel_context *ce;
+
+	ENGINE_TRACE(engine, "\n");
+
+	intel_gt_pm_get(engine->gt);
+
+	/* Discard stale context state from across idling */
+	ce = engine->kernel_context;
+	if (ce) {
+		GEM_BUG_ON(test_bit(CONTEXT_VALID_BIT, &ce->flags));
+
+		/* First poison the image to verify we never fully trust it */
+		if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) && ce->state) {
+			struct drm_i915_gem_object *obj = ce->state->obj;
+			int type = i915_coherent_map_type(engine->i915);
+			void *map;
+
+			map = i915_gem_object_pin_map(obj, type);
+			if (!IS_ERR(map)) {
+				memset(map, CONTEXT_REDZONE, obj->base.size);
+				i915_gem_object_flush_map(obj);
+				i915_gem_object_unpin_map(obj);
+			}
+		}
+
+		ce->ops->reset(ce);
+	}
+
+	if (engine->unpark)
+		engine->unpark(engine);
+
+	intel_engine_unpark_heartbeat(engine);
+	return 0;
+}
+
+#if IS_ENABLED(CONFIG_LOCKDEP)
+
+static inline unsigned long __timeline_mark_lock(struct intel_context *ce)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	mutex_acquire(&ce->timeline->mutex.dep_map, 2, 0, _THIS_IP_);
+
+	return flags;
+}
+
+static inline void __timeline_mark_unlock(struct intel_context *ce,
+					  unsigned long flags)
+{
+	mutex_release(&ce->timeline->mutex.dep_map, _THIS_IP_);
+	local_irq_restore(flags);
+}
+
+#else
+
+static inline unsigned long __timeline_mark_lock(struct intel_context *ce)
+{
+	return 0;
+}
+
+static inline void __timeline_mark_unlock(struct intel_context *ce,
+					  unsigned long flags)
+{
+}
+
+#endif /* !IS_ENABLED(CONFIG_LOCKDEP) */
+
+static void duration(struct dma_fence *fence, struct dma_fence_cb *cb)
+{
+	struct i915_request *rq = to_request(fence);
+
+	ewma__engine_latency_add(&rq->engine->latency,
+				 ktime_us_delta(rq->fence.timestamp,
+						rq->duration.emitted));
+}
+
+static void
+__queue_and_release_pm(struct i915_request *rq,
+		       struct intel_timeline *tl,
+		       struct intel_engine_cs *engine)
+{
+	struct intel_gt_timelines *timelines = &engine->gt->timelines;
+
+	ENGINE_TRACE(engine, "parking\n");
+
+	/*
+	 * We have to serialise all potential retirement paths with our
+	 * submission, as we don't want to underflow either the
+	 * engine->wakeref.counter or our timeline->active_count.
+	 *
+	 * Equally, we cannot allow a new submission to start until
+	 * after we finish queueing, nor could we allow that submitter
+	 * to retire us before we are ready!
+	 */
+	spin_lock(&timelines->lock);
+
+	/* Let intel_gt_retire_requests() retire us (acquired under lock) */
+	if (!atomic_fetch_inc(&tl->active_count))
+		list_add_tail(&tl->link, &timelines->active_list);
+
+	/* Hand the request over to HW and so engine_retire() */
+	__i915_request_queue(rq, NULL);
+
+	/* Let new submissions commence (and maybe retire this timeline) */
+	__intel_wakeref_defer_park(&engine->wakeref);
+
+	spin_unlock(&timelines->lock);
+}
+
+static bool switch_to_kernel_context(struct intel_engine_cs *engine)
+{
+	struct intel_context *ce = engine->kernel_context;
+	struct i915_request *rq;
+	unsigned long flags;
+	bool result = true;
+
+	/* GPU is pointing to the void, as good as in the kernel context. */
+	if (intel_gt_is_wedged(engine->gt))
+		return true;
+
+	GEM_BUG_ON(!intel_context_is_barrier(ce));
+	GEM_BUG_ON(ce->timeline->hwsp_ggtt != engine->status_page.vma);
+
+	/* Already inside the kernel context, safe to power down. */
+	if (engine->wakeref_serial == engine->serial)
+		return true;
+
+	/*
+	 * Note, we do this without taking the timeline->mutex. We cannot
+	 * as we may be called while retiring the kernel context and so
+	 * already underneath the timeline->mutex. Instead we rely on the
+	 * exclusive property of the __engine_park that prevents anyone
+	 * else from creating a request on this engine. This also requires
+	 * that the ring is empty and we avoid any waits while constructing
+	 * the context, as they assume protection by the timeline->mutex.
+	 * This should hold true as we can only park the engine after
+	 * retiring the last request, thus all rings should be empty and
+	 * all timelines idle.
+	 *
+	 * For unlocking, there are 2 other parties and the GPU who have a
+	 * stake here.
+	 *
+	 * A new gpu user will be waiting on the engine-pm to start their
+	 * engine_unpark. New waiters are predicated on engine->wakeref.count
+	 * and so intel_wakeref_defer_park() acts like a mutex_unlock of the
+	 * engine->wakeref.
+	 *
+	 * The other party is intel_gt_retire_requests(), which is walking the
+	 * list of active timelines looking for completions. Meanwhile as soon
+	 * as we call __i915_request_queue(), the GPU may complete our request.
+	 * Ergo, if we put ourselves on the timelines.active_list
+	 * (se intel_timeline_enter()) before we increment the
+	 * engine->wakeref.count, we may see the request completion and retire
+	 * it causing an underflow of the engine->wakeref.
+	 */
+	flags = __timeline_mark_lock(ce);
+	GEM_BUG_ON(atomic_read(&ce->timeline->active_count) < 0);
+
+	rq = __i915_request_create(ce, GFP_NOWAIT);
+	if (IS_ERR(rq))
+		/* Context switch failed, hope for the best! Maybe reset? */
+		goto out_unlock;
+
+	/* Check again on the next retirement. */
+	engine->wakeref_serial = engine->serial + 1;
+	i915_request_add_active_barriers(rq);
+
+	/* Install ourselves as a preemption barrier */
+	rq->sched.attr.priority = I915_PRIORITY_BARRIER;
+	if (likely(!__i915_request_commit(rq))) { /* engine should be idle! */
+		/*
+		 * Use an interrupt for precise measurement of duration,
+		 * otherwise we rely on someone else retiring all the requests
+		 * which may delay the signaling (i.e. we will likely wait
+		 * until the background request retirement running every
+		 * second or two).
+		 */
+		BUILD_BUG_ON(sizeof(rq->duration) > sizeof(rq->submitq));
+		dma_fence_add_callback(&rq->fence, &rq->duration.cb, duration);
+		rq->duration.emitted = ktime_get();
+	}
+
+	/* Expose ourselves to the world */
+	__queue_and_release_pm(rq, ce->timeline, engine);
+
+	result = false;
+out_unlock:
+	__timeline_mark_unlock(ce, flags);
+	return result;
+}
+
+static void call_idle_barriers(struct intel_engine_cs *engine)
+{
+	struct llist_node *node, *next;
+
+	llist_for_each_safe(node, next, llist_del_all(&engine->barrier_tasks)) {
+		struct dma_fence_cb *cb =
+			container_of((struct list_head *)node,
+				     typeof(*cb), node);
+
+		cb->func(ERR_PTR(-EAGAIN), cb);
+	}
+}
+
+static int __engine_park(struct intel_wakeref *wf)
+{
+	struct intel_engine_cs *engine =
+		container_of(wf, typeof(*engine), wakeref);
+
+	engine->saturated = 0;
+
+	/*
+	 * If one and only one request is completed between pm events,
+	 * we know that we are inside the kernel context and it is
+	 * safe to power down. (We are paranoid in case that runtime
+	 * suspend causes corruption to the active context image, and
+	 * want to avoid that impacting userspace.)
+	 */
+	if (!switch_to_kernel_context(engine))
+		return -EBUSY;
+
+	ENGINE_TRACE(engine, "parked\n");
+
+	call_idle_barriers(engine); /* cleanup after wedging */
+
+	intel_engine_park_heartbeat(engine);
+	intel_breadcrumbs_park(engine->breadcrumbs);
+
+	/* Must be reset upon idling, or we may miss the busy wakeup. */
+	GEM_BUG_ON(engine->execlists.queue_priority_hint != INT_MIN);
+
+	if (engine->park)
+		engine->park(engine);
+
+	engine->execlists.no_priolist = false;
+
+	/* While gt calls i915_vma_parked(), we have to break the lock cycle */
+	intel_gt_pm_put_async(engine->gt);
+	return 0;
+}
+
+static const struct intel_wakeref_ops wf_ops = {
+	.get = __engine_unpark,
+	.put = __engine_park,
+};
+
+void intel_engine_init__pm(struct intel_engine_cs *engine)
+{
+	struct intel_runtime_pm *rpm = engine->uncore->rpm;
+
+	intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
+	intel_engine_init_heartbeat(engine);
+}
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftest_engine_pm.c"
+#endif