Commit 3ef71149 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Introduce i915_timeline.mutex 



A simple mutex used for guarding the flow of requests in and out of the
timeline. In the short-term, it will be used only to guard the addition
of requests into the timeline, taken on alloc and released on commit so
that only one caller can construct a request into the timeline
(important as the seqno and ring pointers must be serialised). This will
be used by observers to ensure that the seqno/hwsp is stable. Later,
when we have reduced retiring to only operate on a single timeline at a
time, we can then use the mutex as the sole guard required for retiring.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190301110547.14758-2-chris@chris-wilson.co.uk
parent b5773a36

drivers/gpu/drm/i915/i915_request.c

+5 −1
Original line number Diff line number Diff line
@@ -563,6 +563,7 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx) 
		return ERR_CAST(ce);



	reserve_gt(i915);

	mutex_lock(&ce->ring->timeline->mutex);



	/* Move our oldest request to the slab-cache (if not in use!) */

	rq = list_first_entry(&ce->ring->request_list, typeof(*rq), ring_link);
@@ -688,6 +689,7 @@ err_unwind: 


	kmem_cache_free(global.slab_requests, rq);

err_unreserve:

	mutex_unlock(&ce->ring->timeline->mutex);

	unreserve_gt(i915);

	intel_context_unpin(ce);

	return ERR_PTR(ret);
@@ -880,7 +882,7 @@ void i915_request_add(struct i915_request *request) 
	GEM_TRACE("%s fence %llx:%lld\n",

		  engine->name, request->fence.context, request->fence.seqno);



	lockdep_assert_held(&request->i915->drm.struct_mutex);

	lockdep_assert_held(&request->timeline->mutex);

	trace_i915_request_add(request);



	/*
@@ -991,6 +993,8 @@ void i915_request_add(struct i915_request *request) 
	 */

	if (prev && i915_request_completed(prev))

		i915_request_retire_upto(prev);



	mutex_unlock(&request->timeline->mutex);

}



static unsigned long local_clock_us(unsigned int *cpu)

drivers/gpu/drm/i915/i915_timeline.c

+1 −0
Original line number Diff line number Diff line
@@ -162,6 +162,7 @@ int i915_timeline_init(struct drm_i915_private *i915, 
	timeline->fence_context = dma_fence_context_alloc(1);



	spin_lock_init(&timeline->lock);

	mutex_init(&timeline->mutex);



	INIT_ACTIVE_REQUEST(&timeline->barrier);

	INIT_ACTIVE_REQUEST(&timeline->last_request);

drivers/gpu/drm/i915/i915_timeline.h

+2 −0
Original line number Diff line number Diff line
@@ -44,6 +44,8 @@ struct i915_timeline { 
#define TIMELINE_CLIENT 0 /* default subclass */

#define TIMELINE_ENGINE 1



	struct mutex mutex; /* protects the flow of requests */



	unsigned int pin_count;

	const u32 *hwsp_seqno;

	struct i915_vma *hwsp_ggtt;

drivers/gpu/drm/i915/selftests/i915_request.c

+1 −3
Original line number Diff line number Diff line
@@ -141,14 +141,12 @@ static int igt_fence_wait(void *arg) 
		err = -ENOMEM;

		goto out_locked;

	}

	mutex_unlock(&i915->drm.struct_mutex); /* safe as we are single user */



	if (dma_fence_wait_timeout(&request->fence, false, T) != -ETIME) {

		pr_err("fence wait success before submit (expected timeout)!\n");

		goto out_device;

		goto out_locked;

	}



	mutex_lock(&i915->drm.struct_mutex);

	i915_request_add(request);

	mutex_unlock(&i915->drm.struct_mutex);

drivers/gpu/drm/i915/selftests/mock_timeline.c

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ void mock_timeline_init(struct i915_timeline *timeline, u64 context) 
	timeline->fence_context = context;



	spin_lock_init(&timeline->lock);

	mutex_init(&timeline->mutex);



	INIT_ACTIVE_REQUEST(&timeline->barrier);

	INIT_ACTIVE_REQUEST(&timeline->last_request);

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