Revert "drm/amdgpu: remove fence fallback"

This reverts commit 9b0df0937a852d299fbe42a5939c9a8a4cc83c55.
This commit breaks KCQ IB test and S3 on Polaris 11.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -146,6 +146,7 @@ extern int amdgpu_cik_support;
 #define AMDGPU_DEFAULT_GTT_SIZE_MB		3072ULL /* 3GB by default */
 #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS	        3000
 #define AMDGPU_MAX_USEC_TIMEOUT			100000	/* 100 ms */
+#define AMDGPU_FENCE_JIFFIES_TIMEOUT		(HZ / 2)
 /* AMDGPU_IB_POOL_SIZE must be a power of 2 */
 #define AMDGPU_IB_POOL_SIZE			16
 #define AMDGPU_DEBUGFS_MAX_COMPONENTS		32

drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c

@@ -195,6 +195,19 @@ int amdgpu_fence_emit_polling(struct amdgpu_ring *ring, uint32_t *s)
 	return 0;
 }
 
+/**
+ * amdgpu_fence_schedule_fallback - schedule fallback check
+ *
+ * @ring: pointer to struct amdgpu_ring
+ *
+ * Start a timer as fallback to our interrupts.
+ */
+static void amdgpu_fence_schedule_fallback(struct amdgpu_ring *ring)
+{
+	mod_timer(&ring->fence_drv.fallback_timer,
+		  jiffies + AMDGPU_FENCE_JIFFIES_TIMEOUT);
+}
+
 /**
  * amdgpu_fence_process - check for fence activity
  *
@@ -216,6 +229,9 @@ void amdgpu_fence_process(struct amdgpu_ring *ring)
 
 	} while (atomic_cmpxchg(&drv->last_seq, last_seq, seq) != last_seq);
 
+	if (seq != ring->fence_drv.sync_seq)
+		amdgpu_fence_schedule_fallback(ring);
+
 	if (unlikely(seq == last_seq))
 		return;
 
@@ -246,6 +262,21 @@ void amdgpu_fence_process(struct amdgpu_ring *ring)
 	} while (last_seq != seq);
 }
 
+/**
+ * amdgpu_fence_fallback - fallback for hardware interrupts
+ *
+ * @work: delayed work item
+ *
+ * Checks for fence activity.
+ */
+static void amdgpu_fence_fallback(struct timer_list *t)
+{
+	struct amdgpu_ring *ring = from_timer(ring, t,
+					      fence_drv.fallback_timer);
+
+	amdgpu_fence_process(ring);
+}
+
 /**
  * amdgpu_fence_wait_empty - wait for all fences to signal
  *
@@ -393,6 +424,8 @@ int amdgpu_fence_driver_init_ring(struct amdgpu_ring *ring,
 	atomic_set(&ring->fence_drv.last_seq, 0);
 	ring->fence_drv.initialized = false;
 
+	timer_setup(&ring->fence_drv.fallback_timer, amdgpu_fence_fallback, 0);
+
 	ring->fence_drv.num_fences_mask = num_hw_submission * 2 - 1;
 	spin_lock_init(&ring->fence_drv.lock);
 	ring->fence_drv.fences = kcalloc(num_hw_submission * 2, sizeof(void *),
@@ -468,6 +501,7 @@ void amdgpu_fence_driver_fini(struct amdgpu_device *adev)
 		amdgpu_irq_put(adev, ring->fence_drv.irq_src,
 			       ring->fence_drv.irq_type);
 		drm_sched_fini(&ring->sched);
+		del_timer_sync(&ring->fence_drv.fallback_timer);
 		for (j = 0; j <= ring->fence_drv.num_fences_mask; ++j)
 			dma_fence_put(ring->fence_drv.fences[j]);
 		kfree(ring->fence_drv.fences);
@@ -560,6 +594,27 @@ static const char *amdgpu_fence_get_timeline_name(struct dma_fence *f)
 	return (const char *)fence->ring->name;
 }
 
+/**
+ * amdgpu_fence_enable_signaling - enable signalling on fence
+ * @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.
+ */
+static bool amdgpu_fence_enable_signaling(struct dma_fence *f)
+{
+	struct amdgpu_fence *fence = to_amdgpu_fence(f);
+	struct amdgpu_ring *ring = fence->ring;
+
+	if (!timer_pending(&ring->fence_drv.fallback_timer))
+		amdgpu_fence_schedule_fallback(ring);
+
+	DMA_FENCE_TRACE(&fence->base, "armed on ring %i!\n", ring->idx);
+
+	return true;
+}
+
 /**
  * amdgpu_fence_free - free up the fence memory
  *
@@ -590,6 +645,7 @@ static void amdgpu_fence_release(struct dma_fence *f)
 static const struct dma_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,
 	.release = amdgpu_fence_release,
 };
 

drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h

@@ -77,6 +77,7 @@ struct amdgpu_fence_driver {
 	bool				initialized;
 	struct amdgpu_irq_src		*irq_src;
 	unsigned			irq_type;
+	struct timer_list		fallback_timer;
 	unsigned			num_fences_mask;
 	spinlock_t			lock;
 	struct dma_fence		**fences;