linux-kernel - [PATCH] drm/msm: Remove exclusive-fence hack

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Message-Id: <20221101214051.159988-1-robdclark@gmail.com>
Date:   Tue,  1 Nov 2022 14:40:51 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        linux-kernel@...r.kernel.org (open list),
        linux-media@...r.kernel.org (open list:DMA BUFFER SHARING FRAMEWORK),
        linaro-mm-sig@...ts.linaro.org (moderated list:DMA BUFFER SHARING
        FRAMEWORK)
Subject: [PATCH] drm/msm: Remove exclusive-fence hack

From: Rob Clark <robdclark@...omium.org>

The workaround was initially necessary due to dma_resv having only a
single exclusive fence slot, yet whe don't necessarily know what order
the gpu scheduler will schedule jobs.  Unfortunately this workaround
also has the result of forcing implicit sync, even when userspace does
not want it.

However, since commit 047a1b877ed4 ("dma-buf & drm/amdgpu: remove
dma_resv workaround") the workaround is no longer needed.  So remove
it.  This effectively reverts commit f1b3f696a084 ("drm/msm: Don't
break exclusive fence ordering")

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_gem_submit.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 5599d93ec0d2..cc48f73adadf 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -334,8 +334,7 @@ static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
 		if (ret)
 			return ret;
 
-		/* exclusive fences must be ordered */
-		if (no_implicit && !write)
+		if (no_implicit)
 			continue;
 
 		ret = drm_sched_job_add_implicit_dependencies(&submit->base,
-- 
2.38.1