drm/amdgpu: add a helper to calculate ring distance

Add a helper to calculate the distance in DWs between
two wptrs.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 12 insertions, 6 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index cb0fb1a989d2..1abd8fdb5cef 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -522,6 +522,17 @@ static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring,
 	ring->count_dw -= count_dw;
 }
 
+static inline unsigned int amdgpu_ring_get_dw_distance(struct amdgpu_ring *ring,
+						       u64 start_wptr, u64 end_wptr)
+{
+	unsigned int start = start_wptr & ring->buf_mask;
+	unsigned int end = end_wptr & ring->buf_mask;
+
+	if (end < start)
+		end += ring->ring_size >> 2;
+	return end - start;
+}
+
 /**
  * amdgpu_ring_patch_cond_exec - patch dw count of conditional execute
  * @ring: amdgpu_ring structure
@@ -532,18 +543,13 @@ static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring,
 static inline void amdgpu_ring_patch_cond_exec(struct amdgpu_ring *ring,
 					       unsigned int offset)
 {
-	unsigned cur;
-
 	if (!ring->funcs->init_cond_exec)
 		return;
 
 	WARN_ON(offset > ring->buf_mask);
 	WARN_ON(ring->ring[offset] != 0);
 
-	cur = (ring->wptr - 1) & ring->buf_mask;
-	if (cur < offset)
-		cur += ring->ring_size >> 2;
-	ring->ring[offset] = cur - offset;
+	ring->ring[offset] = amdgpu_ring_get_dw_distance(ring, offset, ring->wptr - 1);
 }
 
 int amdgpu_ring_test_helper(struct amdgpu_ring *ring);