Merge tag 'for-v4.6-rc/omap-fixes-a' of git://git.kernel.org/pub/scm/linux/kernel/git/pjw/omap-pending into omap-for-v4.6/fixes

ARM: OMAP2+: first hwmod fix for v4.6-rc

Fix a longstanding bug in the hwmod code that could cause
hardware SYSCONFIG register values to not match the kernel's
idea of what they should be, and that could result in lower
performance during IP block idle entry.

Basic build, boot, and PM test logs are available here:

http://www.pwsan.com/omap/testlogs/omap-hwmod-fixes-a-for-v4.6-rc/20160326231727/

1 files changed, 190 insertions, 361 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index 3671f9f220bd..4303b447efe8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -47,9 +47,30 @@
  * that the the relevant GPU caches have been flushed.
  */
 
+struct amdgpu_fence {
+	struct fence base;
+
+	/* RB, DMA, etc. */
+	struct amdgpu_ring		*ring;
+};
+
 static struct kmem_cache *amdgpu_fence_slab;
 static atomic_t amdgpu_fence_slab_ref = ATOMIC_INIT(0);
 
+/*
+ * Cast helper
+ */
+static const struct fence_ops amdgpu_fence_ops;
+static inline struct amdgpu_fence *to_amdgpu_fence(struct fence *f)
+{
+	struct amdgpu_fence *__f = container_of(f, struct amdgpu_fence, base);
+
+	if (__f->base.ops == &amdgpu_fence_ops)
+		return __f;
+
+	return NULL;
+}
+
 /**
  * amdgpu_fence_write - write a fence value
  *
@@ -82,7 +103,7 @@ static u32 amdgpu_fence_read(struct amdgpu_ring *ring)
 	if (drv->cpu_addr)
 		seq = le32_to_cpu(*drv->cpu_addr);
 	else
-		seq = lower_32_bits(atomic64_read(&drv->last_seq));
+		seq = atomic_read(&drv->last_seq);
 
 	return seq;
 }
@@ -91,32 +112,41 @@ static u32 amdgpu_fence_read(struct amdgpu_ring *ring)
  * amdgpu_fence_emit - emit a fence on the requested ring
  *
  * @ring: ring the fence is associated with
- * @owner: creator of the fence
- * @fence: amdgpu fence object
+ * @f: resulting fence object
  *
  * Emits a fence command on the requested ring (all asics).
  * Returns 0 on success, -ENOMEM on failure.
  */
-int amdgpu_fence_emit(struct amdgpu_ring *ring, void *owner,
-		      struct amdgpu_fence **fence)
+int amdgpu_fence_emit(struct amdgpu_ring *ring, struct fence **f)
 {
 	struct amdgpu_device *adev = ring->adev;
+	struct amdgpu_fence *fence;
+	struct fence **ptr;
+	uint32_t seq;
 
-	/* we are protected by the ring emission mutex */
-	*fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_KERNEL);
-	if ((*fence) == NULL) {
+	fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_KERNEL);
+	if (fence == NULL)
 		return -ENOMEM;
-	}
-	(*fence)->seq = ++ring->fence_drv.sync_seq[ring->idx];
-	(*fence)->ring = ring;
-	(*fence)->owner = owner;
-	fence_init(&(*fence)->base, &amdgpu_fence_ops,
-		&ring->fence_drv.fence_queue.lock,
-		adev->fence_context + ring->idx,
-		(*fence)->seq);
+
+	seq = ++ring->fence_drv.sync_seq;
+	fence->ring = ring;
+	fence_init(&fence->base, &amdgpu_fence_ops,
+		   &ring->fence_drv.lock,
+		   adev->fence_context + ring->idx,
+		   seq);
 	amdgpu_ring_emit_fence(ring, ring->fence_drv.gpu_addr,
-			       (*fence)->seq,
-			       AMDGPU_FENCE_FLAG_INT);
+			       seq, AMDGPU_FENCE_FLAG_INT);
+
+	ptr = &ring->fence_drv.fences[seq & ring->fence_drv.num_fences_mask];
+	/* This function can't be called concurrently anyway, otherwise
+	 * emitting the fence would mess up the hardware ring buffer.
+	 */
+	BUG_ON(rcu_dereference_protected(*ptr, 1));
+
+	rcu_assign_pointer(*ptr, fence_get(&fence->base));
+
+	*f = &fence->base;
+
 	return 0;
 }
 
@@ -134,89 +164,48 @@ static void amdgpu_fence_schedule_fallback(struct amdgpu_ring *ring)
 }
 
 /**
- * amdgpu_fence_activity - check for fence activity
+ * amdgpu_fence_process - check for fence activity
  *
  * @ring: pointer to struct amdgpu_ring
  *
  * Checks the current fence value and calculates the last
- * signalled fence value. Returns true if activity occured
- * on the ring, and the fence_queue should be waken up.
+ * signalled fence value. Wakes the fence queue if the
+ * sequence number has increased.
  */
-static bool amdgpu_fence_activity(struct amdgpu_ring *ring)
+void amdgpu_fence_process(struct amdgpu_ring *ring)
 {
-	uint64_t seq, last_seq, last_emitted;
-	unsigned count_loop = 0;
-	bool wake = false;
-
-	/* Note there is a scenario here for an infinite loop but it's
-	 * very unlikely to happen. For it to happen, the current polling
-	 * process need to be interrupted by another process and another
-	 * process needs to update the last_seq btw the atomic read and
-	 * xchg of the current process.
-	 *
-	 * More over for this to go in infinite loop there need to be
-	 * continuously new fence signaled ie amdgpu_fence_read needs
-	 * to return a different value each time for both the currently
-	 * polling process and the other process that xchg the last_seq
-	 * btw atomic read and xchg of the current process. And the
-	 * value the other process set as last seq must be higher than
-	 * the seq value we just read. Which means that current process
-	 * need to be interrupted after amdgpu_fence_read and before
-	 * atomic xchg.
-	 *
-	 * To be even more safe we count the number of time we loop and
-	 * we bail after 10 loop just accepting the fact that we might
-	 * have temporarly set the last_seq not to the true real last
-	 * seq but to an older one.
-	 */
-	last_seq = atomic64_read(&ring->fence_drv.last_seq);
+	struct amdgpu_fence_driver *drv = &ring->fence_drv;
+	uint32_t seq, last_seq;
+	int r;
+
 	do {
-		last_emitted = ring->fence_drv.sync_seq[ring->idx];
+		last_seq = atomic_read(&ring->fence_drv.last_seq);
 		seq = amdgpu_fence_read(ring);
-		seq |= last_seq & 0xffffffff00000000LL;
-		if (seq < last_seq) {
-			seq &= 0xffffffff;
-			seq |= last_emitted & 0xffffffff00000000LL;
-		}
 
-		if (seq <= last_seq || seq > last_emitted) {
-			break;
-		}
-		/* If we loop over we don't want to return without
-		 * checking if a fence is signaled as it means that the
-		 * seq we just read is different from the previous on.
-		 */
-		wake = true;
-		last_seq = seq;
-		if ((count_loop++) > 10) {
-			/* We looped over too many time leave with the
-			 * fact that we might have set an older fence
-			 * seq then the current real last seq as signaled
-			 * by the hw.
-			 */
-			break;
-		}
-	} while (atomic64_xchg(&ring->fence_drv.last_seq, seq) > seq);
+	} while (atomic_cmpxchg(&drv->last_seq, last_seq, seq) != last_seq);
 
-	if (seq < last_emitted)
+	if (seq != ring->fence_drv.sync_seq)
 		amdgpu_fence_schedule_fallback(ring);
 
-	return wake;
-}
+	while (last_seq != seq) {
+		struct fence *fence, **ptr;
 
-/**
- * amdgpu_fence_process - process a fence
- *
- * @adev: amdgpu_device pointer
- * @ring: ring index the fence is associated with
- *
- * Checks the current fence value and wakes the fence queue
- * if the sequence number has increased (all asics).
- */
-void amdgpu_fence_process(struct amdgpu_ring *ring)
-{
-	if (amdgpu_fence_activity(ring))
-		wake_up_all(&ring->fence_drv.fence_queue);
+		ptr = &drv->fences[++last_seq & drv->num_fences_mask];
+
+		/* There is always exactly one thread signaling this fence slot */
+		fence = rcu_dereference_protected(*ptr, 1);
+		rcu_assign_pointer(*ptr, NULL);
+
+		BUG_ON(!fence);
+
+		r = fence_signal(fence);
+		if (!r)
+			FENCE_TRACE(fence, "signaled from irq context\n");
+		else
+			BUG();
+
+		fence_put(fence);
+	}
 }
 
 /**
@@ -234,83 +223,6 @@ static void amdgpu_fence_fallback(unsigned long arg)
 }
 
 /**
- * amdgpu_fence_seq_signaled - check if a fence sequence number has signaled
- *
- * @ring: ring the fence is associated with
- * @seq: sequence number
- *
- * Check if the last signaled fence sequnce number is >= the requested
- * sequence number (all asics).
- * Returns true if the fence has signaled (current fence value
- * is >= requested value) or false if it has not (current fence
- * value is < the requested value.  Helper function for
- * amdgpu_fence_signaled().
- */
-static bool amdgpu_fence_seq_signaled(struct amdgpu_ring *ring, u64 seq)
-{
-	if (atomic64_read(&ring->fence_drv.last_seq) >= seq)
-		return true;
-
-	/* poll new last sequence at least once */
-	amdgpu_fence_process(ring);
-	if (atomic64_read(&ring->fence_drv.last_seq) >= seq)
-		return true;
-
-	return false;
-}
-
-/*
- * amdgpu_ring_wait_seq_timeout - wait for seq of the specific ring to signal
- * @ring: ring to wait on for the seq number
- * @seq: seq number wait for
- *
- * return value:
- * 0: seq signaled, and gpu not hang
- * -EDEADL: GPU hang detected
- * -EINVAL: some paramter is not valid
- */
-static int amdgpu_fence_ring_wait_seq(struct amdgpu_ring *ring, uint64_t seq)
-{
-	bool signaled = false;
-
-	BUG_ON(!ring);
-	if (seq > ring->fence_drv.sync_seq[ring->idx])
-		return -EINVAL;
-
-	if (atomic64_read(&ring->fence_drv.last_seq) >= seq)
-		return 0;
-
-	amdgpu_fence_schedule_fallback(ring);
-	wait_event(ring->fence_drv.fence_queue, (
-		   (signaled = amdgpu_fence_seq_signaled(ring, seq))));
-
-	if (signaled)
-		return 0;
-	else
-		return -EDEADLK;
-}
-
-/**
- * amdgpu_fence_wait_next - wait for the next fence to signal
- *
- * @adev: amdgpu device pointer
- * @ring: ring index the fence is associated with
- *
- * Wait for the next fence on the requested ring to signal (all asics).
- * Returns 0 if the next fence has passed, error for all other cases.
- * Caller must hold ring lock.
- */
-int amdgpu_fence_wait_next(struct amdgpu_ring *ring)
-{
-	uint64_t seq = atomic64_read(&ring->fence_drv.last_seq) + 1ULL;
-
-	if (seq >= ring->fence_drv.sync_seq[ring->idx])
-		return -ENOENT;
-
-	return amdgpu_fence_ring_wait_seq(ring, seq);
-}
-
-/**
  * amdgpu_fence_wait_empty - wait for all fences to signal
  *
  * @adev: amdgpu device pointer
@@ -318,16 +230,28 @@ int amdgpu_fence_wait_next(struct amdgpu_ring *ring)
  *
  * Wait for all fences on the requested ring to signal (all asics).
  * Returns 0 if the fences have passed, error for all other cases.
- * Caller must hold ring lock.
  */
 int amdgpu_fence_wait_empty(struct amdgpu_ring *ring)
 {
-	uint64_t seq = ring->fence_drv.sync_seq[ring->idx];
+	uint64_t seq = ACCESS_ONCE(ring->fence_drv.sync_seq);
+	struct fence *fence, **ptr;
+	int r;
 
 	if (!seq)
 		return 0;
 
-	return amdgpu_fence_ring_wait_seq(ring, seq);
+	ptr = &ring->fence_drv.fences[seq & ring->fence_drv.num_fences_mask];
+	rcu_read_lock();
+	fence = rcu_dereference(*ptr);
+	if (!fence || !fence_get_rcu(fence)) {
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	r = fence_wait(fence, false);
+	fence_put(fence);
+	return r;
 }
 
 /**
@@ -347,75 +271,10 @@ unsigned amdgpu_fence_count_emitted(struct amdgpu_ring *ring)
 	 * but it's ok to report slightly wrong fence count here.
 	 */
 	amdgpu_fence_process(ring);
-	emitted = ring->fence_drv.sync_seq[ring->idx]
-		- atomic64_read(&ring->fence_drv.last_seq);
-	/* to avoid 32bits warp around */
-	if (emitted > 0x10000000)
-		emitted = 0x10000000;
-
-	return (unsigned)emitted;
-}
-
-/**
- * amdgpu_fence_need_sync - do we need a semaphore
- *
- * @fence: amdgpu fence object
- * @dst_ring: which ring to check against
- *
- * Check if the fence needs to be synced against another ring
- * (all asics).  If so, we need to emit a semaphore.
- * Returns true if we need to sync with another ring, false if
- * not.
- */
-bool amdgpu_fence_need_sync(struct amdgpu_fence *fence,
-			    struct amdgpu_ring *dst_ring)
-{
-	struct amdgpu_fence_driver *fdrv;
-
-	if (!fence)
-		return false;
-
-	if (fence->ring == dst_ring)
-		return false;
-
-	/* we are protected by the ring mutex */
-	fdrv = &dst_ring->fence_drv;
-	if (fence->seq <= fdrv->sync_seq[fence->ring->idx])
-		return false;
-
-	return true;
-}
-
-/**
- * amdgpu_fence_note_sync - record the sync point
- *
- * @fence: amdgpu fence object
- * @dst_ring: which ring to check against
- *
- * Note the sequence number at which point the fence will
- * be synced with the requested ring (all asics).
- */
-void amdgpu_fence_note_sync(struct amdgpu_fence *fence,
-			    struct amdgpu_ring *dst_ring)
-{
-	struct amdgpu_fence_driver *dst, *src;
-	unsigned i;
-
-	if (!fence)
-		return;
-
-	if (fence->ring == dst_ring)
-		return;
-
-	/* we are protected by the ring mutex */
-	src = &fence->ring->fence_drv;
-	dst = &dst_ring->fence_drv;
-	for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
-		if (i == dst_ring->idx)
-			continue;
-
-		dst->sync_seq[i] = max(dst->sync_seq[i], src->sync_seq[i]);
-	}
+	emitted = 0x100000000ull;
+	emitted -= atomic_read(&ring->fence_drv.last_seq);
+	emitted += ACCESS_ONCE(ring->fence_drv.sync_seq);
+	return lower_32_bits(emitted);
 }
 
 /**
@@ -447,7 +306,7 @@ int amdgpu_fence_driver_start_ring(struct amdgpu_ring *ring,
 		ring->fence_drv.cpu_addr = adev->uvd.cpu_addr + index;
 		ring->fence_drv.gpu_addr = adev->uvd.gpu_addr + index;
 	}
-	amdgpu_fence_write(ring, atomic64_read(&ring->fence_drv.last_seq));
+	amdgpu_fence_write(ring, atomic_read(&ring->fence_drv.last_seq));
 	amdgpu_irq_get(adev, irq_src, irq_type);
 
 	ring->fence_drv.irq_src = irq_src;
@@ -465,47 +324,55 @@ int amdgpu_fence_driver_start_ring(struct amdgpu_ring *ring,
  * for the requested ring.
  *
  * @ring: ring to init the fence driver on
+ * @num_hw_submission: number of entries on the hardware queue
  *
  * Init the fence driver for the requested ring (all asics).
  * Helper function for amdgpu_fence_driver_init().
  */
-int amdgpu_fence_driver_init_ring(struct amdgpu_ring *ring)
+int amdgpu_fence_driver_init_ring(struct amdgpu_ring *ring,
+				  unsigned num_hw_submission)
 {
-	int i, r;
+	long timeout;
+	int r;
+
+	/* Check that num_hw_submission is a power of two */
+	if ((num_hw_submission & (num_hw_submission - 1)) != 0)
+		return -EINVAL;
 
 	ring->fence_drv.cpu_addr = NULL;
 	ring->fence_drv.gpu_addr = 0;
-	for (i = 0; i < AMDGPU_MAX_RINGS; ++i)
-		ring->fence_drv.sync_seq[i] = 0;
-
-	atomic64_set(&ring->fence_drv.last_seq, 0);
+	ring->fence_drv.sync_seq = 0;
+	atomic_set(&ring->fence_drv.last_seq, 0);
 	ring->fence_drv.initialized = false;
 
 	setup_timer(&ring->fence_drv.fallback_timer, amdgpu_fence_fallback,
 		    (unsigned long)ring);
 
-	init_waitqueue_head(&ring->fence_drv.fence_queue);
-
-	if (amdgpu_enable_scheduler) {
-		long timeout = msecs_to_jiffies(amdgpu_lockup_timeout);
-		if (timeout == 0) {
-			/*
-			 * FIXME:
-			 * Delayed workqueue cannot use it directly,
-			 * so the scheduler will not use delayed workqueue if
-			 * MAX_SCHEDULE_TIMEOUT is set.
-			 * Currently keep it simple and silly.
-			 */
-			timeout = MAX_SCHEDULE_TIMEOUT;
-		}
-		r = amd_sched_init(&ring->sched, &amdgpu_sched_ops,
-				   amdgpu_sched_hw_submission,
-				   timeout, ring->name);
-		if (r) {
-			DRM_ERROR("Failed to create scheduler on ring %s.\n",
-				  ring->name);
-			return r;
-		}
+	ring->fence_drv.num_fences_mask = num_hw_submission - 1;
+	spin_lock_init(&ring->fence_drv.lock);
+	ring->fence_drv.fences = kcalloc(num_hw_submission, sizeof(void *),
+					 GFP_KERNEL);
+	if (!ring->fence_drv.fences)
+		return -ENOMEM;
+
+	timeout = msecs_to_jiffies(amdgpu_lockup_timeout);
+	if (timeout == 0) {
+		/*
+		 * FIXME:
+		 * Delayed workqueue cannot use it directly,
+		 * so the scheduler will not use delayed workqueue if
+		 * MAX_SCHEDULE_TIMEOUT is set.
+		 * Currently keep it simple and silly.
+		 */
+		timeout = MAX_SCHEDULE_TIMEOUT;
+	}
+	r = amd_sched_init(&ring->sched, &amdgpu_sched_ops,
+			   num_hw_submission,
+			   timeout, ring->name);
+	if (r) {
+		DRM_ERROR("Failed to create scheduler on ring %s.\n",
+			  ring->name);
+		return r;
 	}
 
 	return 0;
@@ -548,11 +415,9 @@ int amdgpu_fence_driver_init(struct amdgpu_device *adev)
  */
 void amdgpu_fence_driver_fini(struct amdgpu_device *adev)
 {
-	int i, r;
+	unsigned i, j;
+	int r;
 
-	if (atomic_dec_and_test(&amdgpu_fence_slab_ref))
-		kmem_cache_destroy(amdgpu_fence_slab);
-	mutex_lock(&adev->ring_lock);
 	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
 		struct amdgpu_ring *ring = adev->rings[i];
 
@@ -563,14 +428,18 @@ void amdgpu_fence_driver_fini(struct amdgpu_device *adev)
 			/* no need to trigger GPU reset as we are unloading */
 			amdgpu_fence_driver_force_completion(adev);
 		}
-		wake_up_all(&ring->fence_drv.fence_queue);
 		amdgpu_irq_put(adev, ring->fence_drv.irq_src,
 			       ring->fence_drv.irq_type);
 		amd_sched_fini(&ring->sched);
 		del_timer_sync(&ring->fence_drv.fallback_timer);
+		for (j = 0; j <= ring->fence_drv.num_fences_mask; ++j)
+			fence_put(ring->fence_drv.fences[i]);
+		kfree(ring->fence_drv.fences);
 		ring->fence_drv.initialized = false;
 	}
-	mutex_unlock(&adev->ring_lock);
+
+	if (atomic_dec_and_test(&amdgpu_fence_slab_ref))
+		kmem_cache_destroy(amdgpu_fence_slab);
 }
 
 /**
@@ -585,7 +454,6 @@ void amdgpu_fence_driver_suspend(struct amdgpu_device *adev)
 {
 	int i, r;
 
-	mutex_lock(&adev->ring_lock);
 	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
 		struct amdgpu_ring *ring = adev->rings[i];
 		if (!ring || !ring->fence_drv.initialized)
@@ -602,7 +470,6 @@ void amdgpu_fence_driver_suspend(struct amdgpu_device *adev)
 		amdgpu_irq_put(adev, ring->fence_drv.irq_src,
 			       ring->fence_drv.irq_type);
 	}
-	mutex_unlock(&adev->ring_lock);
 }
 
 /**
@@ -621,7 +488,6 @@ void amdgpu_fence_driver_resume(struct amdgpu_device *adev)
 {
 	int i;
 
-	mutex_lock(&adev->ring_lock);
 	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
 		struct amdgpu_ring *ring = adev->rings[i];
 		if (!ring || !ring->fence_drv.initialized)
@@ -631,7 +497,6 @@ void amdgpu_fence_driver_resume(struct amdgpu_device *adev)
 		amdgpu_irq_get(adev, ring->fence_drv.irq_src,
 			       ring->fence_drv.irq_type);
 	}
-	mutex_unlock(&adev->ring_lock);
 }
 
 /**
@@ -651,7 +516,7 @@ void amdgpu_fence_driver_force_completion(struct amdgpu_device *adev)
 		if (!ring || !ring->fence_drv.initialized)
 			continue;
 
-		amdgpu_fence_write(ring, ring->fence_drv.sync_seq[i]);
+		amdgpu_fence_write(ring, ring->fence_drv.sync_seq);
 	}
 }
 
@@ -671,103 +536,57 @@ static const char *amdgpu_fence_get_timeline_name(struct fence *f)
 }
 
 /**
- * amdgpu_fence_is_signaled - test if fence is signaled
- *
- * @f: fence to test
+ * amdgpu_fence_enable_signaling - enable signalling on fence
+ * @fence: fence
  *
- * Test the fence sequence number if it is already signaled. If it isn't
- * signaled start fence processing. Returns True if the fence is signaled.
+ * This function is called with fence_queue lock held, and adds a callback
+ * to fence_queue that checks if this fence is signaled, and if so it
+ * signals the fence and removes itself.
  */
-static bool amdgpu_fence_is_signaled(struct fence *f)
+static bool amdgpu_fence_enable_signaling(struct fence *f)
 {
 	struct amdgpu_fence *fence = to_amdgpu_fence(f);
 	struct amdgpu_ring *ring = fence->ring;
 
-	if (atomic64_read(&ring->fence_drv.last_seq) >= fence->seq)
-		return true;
-
-	amdgpu_fence_process(ring);
+	if (!timer_pending(&ring->fence_drv.fallback_timer))
+		amdgpu_fence_schedule_fallback(ring);
 
-	if (atomic64_read(&ring->fence_drv.last_seq) >= fence->seq)
-		return true;
+	FENCE_TRACE(&fence->base, "armed on ring %i!\n", ring->idx);
 
-	return false;
+	return true;
 }
 
 /**
- * amdgpu_fence_check_signaled - callback from fence_queue
+ * amdgpu_fence_free - free up the fence memory
+ *
+ * @rcu: RCU callback head
  *
- * this function is called with fence_queue lock held, which is also used
- * for the fence locking itself, so unlocked variants are used for
- * fence_signal, and remove_wait_queue.
+ * Free up the fence memory after the RCU grace period.
  */
-static int amdgpu_fence_check_signaled(wait_queue_t *wait, unsigned mode, int flags, void *key)
+static void amdgpu_fence_free(struct rcu_head *rcu)
 {
-	struct amdgpu_fence *fence;
-	struct amdgpu_device *adev;
-	u64 seq;
-	int ret;
-
-	fence = container_of(wait, struct amdgpu_fence, fence_wake);
-	adev = fence->ring->adev;
-
-	/*
-	 * We cannot use amdgpu_fence_process here because we're already
-	 * in the waitqueue, in a call from wake_up_all.
-	 */
-	seq = atomic64_read(&fence->ring->fence_drv.last_seq);
-	if (seq >= fence->seq) {
-		ret = fence_signal_locked(&fence->base);
-		if (!ret)
-			FENCE_TRACE(&fence->base, "signaled from irq context\n");
-		else
-			FENCE_TRACE(&fence->base, "was already signaled\n");
-
-		__remove_wait_queue(&fence->ring->fence_drv.fence_queue, &fence->fence_wake);
-		fence_put(&fence->base);
-	} else
-		FENCE_TRACE(&fence->base, "pending\n");
-	return 0;
+	struct fence *f = container_of(rcu, struct fence, rcu);
+	struct amdgpu_fence *fence = to_amdgpu_fence(f);
+	kmem_cache_free(amdgpu_fence_slab, fence);
 }
 
 /**
- * amdgpu_fence_enable_signaling - enable signalling on fence
+ * amdgpu_fence_release - callback that fence can be freed
+ *
  * @fence: fence
  *
- * This function is called with fence_queue lock held, and adds a callback
- * to fence_queue that checks if this fence is signaled, and if so it
- * signals the fence and removes itself.
+ * This function is called when the reference count becomes zero.
+ * It just RCU schedules freeing up the fence.
  */
-static bool amdgpu_fence_enable_signaling(struct fence *f)
-{
-	struct amdgpu_fence *fence = to_amdgpu_fence(f);
-	struct amdgpu_ring *ring = fence->ring;
-
-	if (atomic64_read(&ring->fence_drv.last_seq) >= fence->seq)
-		return false;
-
-	fence->fence_wake.flags = 0;
-	fence->fence_wake.private = NULL;
-	fence->fence_wake.func = amdgpu_fence_check_signaled;
-	__add_wait_queue(&ring->fence_drv.fence_queue, &fence->fence_wake);
-	fence_get(f);
-	if (!timer_pending(&ring->fence_drv.fallback_timer))
-		amdgpu_fence_schedule_fallback(ring);
-	FENCE_TRACE(&fence->base, "armed on ring %i!\n", ring->idx);
-	return true;
-}
-
 static void amdgpu_fence_release(struct fence *f)
 {
-	struct amdgpu_fence *fence = to_amdgpu_fence(f);
-	kmem_cache_free(amdgpu_fence_slab, fence);
+	call_rcu(&f->rcu, amdgpu_fence_free);
 }
 
-const struct fence_ops amdgpu_fence_ops = {
+static const struct fence_ops amdgpu_fence_ops = {
 	.get_driver_name = amdgpu_fence_get_driver_name,
 	.get_timeline_name = amdgpu_fence_get_timeline_name,
 	.enable_signaling = amdgpu_fence_enable_signaling,
-	.signaled = amdgpu_fence_is_signaled,
 	.wait = fence_default_wait,
 	.release = amdgpu_fence_release,
 };
@@ -781,7 +600,7 @@ static int amdgpu_debugfs_fence_info(struct seq_file *m, void *data)
 	struct drm_info_node *node = (struct drm_info_node *)m->private;
 	struct drm_device *dev = node->minor->dev;
 	struct amdgpu_device *adev = dev->dev_private;
-	int i, j;
+	int i;
 
 	for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
 		struct amdgpu_ring *ring = adev->rings[i];
@@ -791,31 +610,41 @@ static int amdgpu_debugfs_fence_info(struct seq_file *m, void *data)
 		amdgpu_fence_process(ring);
 
 		seq_printf(m, "--- ring %d (%s) ---\n", i, ring->name);
-		seq_printf(m, "Last signaled fence 0x%016llx\n",
-			   (unsigned long long)atomic64_read(&ring->fence_drv.last_seq));
-		seq_printf(m, "Last emitted        0x%016llx\n",
-			   ring->fence_drv.sync_seq[i]);
-
-		for (j = 0; j < AMDGPU_MAX_RINGS; ++j) {
-			struct amdgpu_ring *other = adev->rings[j];
-			if (i != j && other && other->fence_drv.initialized &&
-			    ring->fence_drv.sync_seq[j])
-				seq_printf(m, "Last sync to ring %d 0x%016llx\n",
-					   j, ring->fence_drv.sync_seq[j]);
-		}
+		seq_printf(m, "Last signaled fence 0x%08x\n",
+			   atomic_read(&ring->fence_drv.last_seq));
+		seq_printf(m, "Last emitted        0x%08x\n",
+			   ring->fence_drv.sync_seq);
 	}
 	return 0;
 }
 
+/**
+ * amdgpu_debugfs_gpu_reset - manually trigger a gpu reset
+ *
+ * Manually trigger a gpu reset at the next fence wait.
+ */
+static int amdgpu_debugfs_gpu_reset(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = (struct drm_info_node *) m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct amdgpu_device *adev = dev->dev_private;
+
+	seq_printf(m, "gpu reset\n");
+	amdgpu_gpu_reset(adev);
+
+	return 0;
+}
+
 static struct drm_info_list amdgpu_debugfs_fence_list[] = {
 	{"amdgpu_fence_info", &amdgpu_debugfs_fence_info, 0, NULL},
+	{"amdgpu_gpu_reset", &amdgpu_debugfs_gpu_reset, 0, NULL}
 };
 #endif
 
 int amdgpu_debugfs_fence_init(struct amdgpu_device *adev)
 {
 #if defined(CONFIG_DEBUG_FS)
-	return amdgpu_debugfs_add_files(adev, amdgpu_debugfs_fence_list, 1);
+	return amdgpu_debugfs_add_files(adev, amdgpu_debugfs_fence_list, 2);
 #else
 	return 0;
 #endif