linux-kernel - [PATCH v2] iommu/arm-smmu: disable PRR on SM8250

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Message-Id: <20250705-iommu-fix-prr-v2-1-406fecc37cf8@oss.qualcomm.com>
Date: Sat, 05 Jul 2025 19:08:33 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Rob Clark <robin.clark@....qualcomm.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>, Joerg Roedel <joro@...tes.org>,
        Bibek Kumar Patro <quic_bibekkum@...cinc.com>
Cc: iommu@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] iommu/arm-smmu: disable PRR on SM8250

On SM8250 / QRB5165-RB5 using PRR bits resets the device, most likely
because of the hyp limitations. Disable PRR support on that platform.

Fixes: 7f2ef1bfc758 ("iommu/arm-smmu: Add support for PRR bit setup")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
I currently don't have access to other devices from these generations.
It might be necessary to apply the same workaround to other platforms.
---
Changes in v2:
- Simplify the workaround as the issue seems to be limited to SM8250
  only (Rob)
- Link to v1: https://lore.kernel.org/r/20250705-iommu-fix-prr-v1-1-ef725033651c@oss.qualcomm.com
---
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index 62874b18f6459ad9a8b0542ab81c24e3e745c53d..53d88646476e9f193a6275d9c3ee3d084c215362 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -355,7 +355,8 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
 	priv->set_prr_addr = NULL;
 
 	if (of_device_is_compatible(np, "qcom,smmu-500") &&
-			of_device_is_compatible(np, "qcom,adreno-smmu")) {
+	    !of_device_is_compatible(np, "qcom,sm8250-smmu-500") &&
+	    of_device_is_compatible(np, "qcom,adreno-smmu")) {
 		priv->set_prr_bit = qcom_adreno_smmu_set_prr_bit;
 		priv->set_prr_addr = qcom_adreno_smmu_set_prr_addr;
 	}

---
base-commit: 7244e36657076b597ac21d118be9c0b0f15fc622
change-id: 20250705-iommu-fix-prr-600451b1d304

Best regards,
-- 
With best wishes
Dmitry