linux-kernel - [PATCH] drm/msm: Fix 0xfffflub in "Refactor address space initialization"

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Message-Id: <20200613042159.109511-1-john.stultz@linaro.org>
Date:   Sat, 13 Jun 2020 04:21:59 +0000
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     John Stultz <john.stultz@...aro.org>,
        Shawn Guo <shawn.guo@...aro.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        freedreno@...ts.freedesktop.org
Subject: [PATCH] drm/msm: Fix 0xfffflub in "Refactor address space initialization"

This week I started seeing GPU crashes on my DragonBoard 845c
which I narrowed down to being caused by commit ccac7ce373c1
("drm/msm: Refactor address space initialization").

Looking through the patch, Jordan and I couldn't find anything
obviously wrong, so I ended up breaking that change up into a
number of smaller logical steps so I could figure out which part
was causing the trouble.

Ends up, visually counting 'f's is hard, esp across a number
of lines:
  0xfffffff != 0xffffffff

This patch corrects the end value we pass in to
msm_gem_address_space_create() in
adreno_iommu_create_address_space() so that it matches the value
used before the problematic patch landed.

With this change, I no longer see the GPU crashes that were
affecting me.

Cc: Shawn Guo <shawn.guo@...aro.org>
Cc: Rob Clark <robdclark@...il.com>
Cc: Sean Paul <sean@...rly.run>
Cc: Jordan Crouse <jcrouse@...eaurora.org>
Cc: freedreno@...ts.freedesktop.org
Fixes: ccac7ce373c1 ("drm/msm: Refactor address space initialization")
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 89673c7ed473..3d4efe684a98 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -194,7 +194,7 @@ adreno_iommu_create_address_space(struct msm_gpu *gpu,
 	struct msm_gem_address_space *aspace;
 
 	aspace = msm_gem_address_space_create(mmu, "gpu", SZ_16M,
-		0xfffffff);
+		0xffffffff);
 
 	if (IS_ERR(aspace) && !IS_ERR(mmu))
 		mmu->funcs->destroy(mmu);
-- 
2.17.1