[PATCH v4 23/23] drm/msm: Don't implicit-sync if only a single ring

[Rob Clark]

From: Rob Clark <robdclark@xxxxxxxxxxxx>

If there is only a single ring (no-preemption), everything is FIFO order
and there is no need to implicit-sync.

Mesa should probably just always use MSM_SUBMIT_NO_IMPLICIT, as behavior
is undefined when fences are not used to synchronize buffer usage across
contexts (which is the only case where multiple different priority rings
could come into play).

Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Reviewed-by: Kristian H. Kristensen <hoegsberg@xxxxxxxxxx>
---
 drivers/gpu/drm/msm/msm_gem_submit.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index d04c349d8112..b6babc7f9bb8 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -283,7 +283,7 @@ static int submit_lock_objects(struct msm_gem_submit *submit)
 	return ret;
 }
 
-static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
+static int submit_fence_sync(struct msm_gem_submit *submit, bool implicit_sync)
 {
 	int i, ret = 0;
 
@@ -303,7 +303,7 @@ static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
 				return ret;
 		}
 
-		if (no_implicit)
+		if (!implicit_sync)
 			continue;
 
 		ret = msm_gem_sync_object(&msm_obj->base, submit->ring->fctx,
@@ -774,7 +774,8 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	if (ret)
 		goto out;
 
-	ret = submit_fence_sync(submit, !!(args->flags & MSM_SUBMIT_NO_IMPLICIT));
+	ret = submit_fence_sync(submit, (gpu->nr_rings > 1) &&
+			!(args->flags & MSM_SUBMIT_NO_IMPLICIT));
 	if (ret)
 		goto out;
 
-- 
2.26.2