[PATCH v4 14/23] drm/msm: Document and rename preempt_lock

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

Before adding another lock, give ring->lock a more descriptive name.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
---
 drivers/gpu/drm/msm/adreno/a5xx_gpu.c     |  4 ++--
 drivers/gpu/drm/msm/adreno/a5xx_preempt.c | 12 ++++++------
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c     |  4 ++--
 drivers/gpu/drm/msm/msm_ringbuffer.c      |  2 +-
 drivers/gpu/drm/msm/msm_ringbuffer.h      |  7 ++++++-
 5 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
index 2180650a03bc..a1b9419a59c9 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
@@ -36,7 +36,7 @@ void a5xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
 		OUT_RING(ring, upper_32_bits(shadowptr(a5xx_gpu, ring)));
 	}
 
-	spin_lock_irqsave(&ring->lock, flags);
+	spin_lock_irqsave(&ring->preempt_lock, flags);
 
 	/* Copy the shadow to the actual register */
 	ring->cur = ring->next;
@@ -44,7 +44,7 @@ void a5xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
 	/* Make sure to wrap wptr if we need to */
 	wptr = get_wptr(ring);
 
-	spin_unlock_irqrestore(&ring->lock, flags);
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
 	/* Make sure everything is posted before making a decision */
 	mb();
diff --git a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
index 7e04509c4e1f..183de1139eeb 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
@@ -45,9 +45,9 @@ static inline void update_wptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 	if (!ring)
 		return;
 
-	spin_lock_irqsave(&ring->lock, flags);
+	spin_lock_irqsave(&ring->preempt_lock, flags);
 	wptr = get_wptr(ring);
-	spin_unlock_irqrestore(&ring->lock, flags);
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
 	gpu_write(gpu, REG_A5XX_CP_RB_WPTR, wptr);
 }
@@ -62,9 +62,9 @@ static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
 		bool empty;
 		struct msm_ringbuffer *ring = gpu->rb[i];
 
-		spin_lock_irqsave(&ring->lock, flags);
+		spin_lock_irqsave(&ring->preempt_lock, flags);
 		empty = (get_wptr(ring) == ring->memptrs->rptr);
-		spin_unlock_irqrestore(&ring->lock, flags);
+		spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
 		if (!empty)
 			return ring;
@@ -132,9 +132,9 @@ void a5xx_preempt_trigger(struct msm_gpu *gpu)
 	}
 
 	/* Make sure the wptr doesn't update while we're in motion */
-	spin_lock_irqsave(&ring->lock, flags);
+	spin_lock_irqsave(&ring->preempt_lock, flags);
 	a5xx_gpu->preempt[ring->id]->wptr = get_wptr(ring);
-	spin_unlock_irqrestore(&ring->lock, flags);
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
 	/* Set the address of the incoming preemption record */
 	gpu_write64(gpu, REG_A5XX_CP_CONTEXT_SWITCH_RESTORE_ADDR_LO,
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 16eaaf0804ca..eb44e0dbef34 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -65,7 +65,7 @@ static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 		OUT_RING(ring, upper_32_bits(shadowptr(a6xx_gpu, ring)));
 	}
 
-	spin_lock_irqsave(&ring->lock, flags);
+	spin_lock_irqsave(&ring->preempt_lock, flags);
 
 	/* Copy the shadow to the actual register */
 	ring->cur = ring->next;
@@ -73,7 +73,7 @@ static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 	/* Make sure to wrap wptr if we need to */
 	wptr = get_wptr(ring);
 
-	spin_unlock_irqrestore(&ring->lock, flags);
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
 	/* Make sure everything is posted before making a decision */
 	mb();
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
index 935bf9b1d941..1b6958e908dc 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.c
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
@@ -46,7 +46,7 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,
 	ring->memptrs_iova = memptrs_iova;
 
 	INIT_LIST_HEAD(&ring->submits);
-	spin_lock_init(&ring->lock);
+	spin_lock_init(&ring->preempt_lock);
 
 	snprintf(name, sizeof(name), "gpu-ring-%d", ring->id);
 
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 0987d6bf848c..4956d1bc5d0e 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -46,7 +46,12 @@ struct msm_ringbuffer {
 	struct msm_rbmemptrs *memptrs;
 	uint64_t memptrs_iova;
 	struct msm_fence_context *fctx;
-	spinlock_t lock;
+
+	/*
+	 * preempt_lock protects preemption and serializes wptr updates against
+	 * preemption.  Can be aquired from irq context.
+	 */
+	spinlock_t preempt_lock;
 };
 
 struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,
-- 
2.26.2