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From:   Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To:     Will Deacon <will@kernel.org>, Robin Murphy <robin.murphy@arm.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jordan Crouse <jcrouse@codeaurora.org>,
        Rob Clark <robdclark@gmail.com>,
        Akhil P Oommen <akhilpo@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>
Cc:     iommu@lists.linux-foundation.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org,
        Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Subject: [PATCHv2 2/2] iommu/arm-smmu-qcom: Move the adreno smmu specific impl earlier
Date:   Fri, 26 Feb 2021 15:25:40 +0530
Message-Id: <c607d71eb0fe507c8b83cc0ea9b393777f22149a.1614332994.git.saiprakash.ranjan@codeaurora.org>
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Adreno(GPU) SMMU and APSS(Application Processor SubSystem) SMMU
both implement "arm,mmu-500" in some QTI SoCs and to run through
adreno smmu specific implementation such as enabling split pagetables
support, we need to match the "qcom,adreno-smmu" compatible first
before apss smmu or else we will be running apps smmu implementation
for adreno smmu and the additional features for adreno smmu is never
set. For ex: we have "qcom,sc7280-smmu-500" compatible for both apps
and adreno smmu implementing "arm,mmu-500", so the adreno smmu
implementation is never reached because the current sequence checks
for apps smmu compatible(qcom,sc7280-smmu-500) first and runs that
specific impl and we never reach adreno smmu specific implementation.

Suggested-by: Akhil P Oommen <akhilpo@codeaurora.org>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index bea3ee0dabc2..03f048aebb80 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -345,11 +345,17 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu)
 {
 	const struct device_node *np = smmu->dev->of_node;
 
-	if (of_match_node(qcom_smmu_impl_of_match, np))
-		return qcom_smmu_create(smmu, &qcom_smmu_impl);
-
+	/*
+	 * Do not change this order of implementation, i.e., first adreno
+	 * smmu impl and then apss smmu since we can have both implementing
+	 * arm,mmu-500 in which case we will miss setting adreno smmu specific
+	 * features if the order is changed.
+	 */
 	if (of_device_is_compatible(np, "qcom,adreno-smmu"))
 		return qcom_smmu_create(smmu, &qcom_adreno_smmu_impl);
 
+	if (of_match_node(qcom_smmu_impl_of_match, np))
+		return qcom_smmu_create(smmu, &qcom_smmu_impl);
+
 	return smmu;
 }
-- 
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