[PATCH AUTOSEL 5.15 39/43] drm/msm: Be more shouty if per-process pgtables aren't working

[Sasha Levin]

From: Rob Clark <robdclark@xxxxxxxxxxxx>

[ Upstream commit 5c054db54c43a5fcb5cc81012361f5e3fac37637 ]

Otherwise it is not always obvious if a dt or iommu change is causing us
to fall back to global pgtable.

Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Patchwork: https://patchwork.freedesktop.org/patch/537359/
Link: https://lore.kernel.org/r/20230516222039.907690-2-robdclark@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/msm/msm_iommu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index a54ed354578b5..ef4da3f0cd22d 100644
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -157,7 +157,12 @@ struct msm_mmu *msm_iommu_pagetable_create(struct msm_mmu *parent)
 	/* Get the pagetable configuration from the domain */
 	if (adreno_smmu->cookie)
 		ttbr1_cfg = adreno_smmu->get_ttbr1_cfg(adreno_smmu->cookie);
-	if (!ttbr1_cfg)
+
+	/*
+	 * If you hit this WARN_ONCE() you are probably missing an entry in
+	 * qcom_smmu_impl_of_match[] in arm-smmu-qcom.c
+	 */
+	if (WARN_ONCE(!ttbr1_cfg, "No per-process page tables"))
 		return ERR_PTR(-ENODEV);
 
 	/*
-- 
2.39.2