Re: [PATCHv2 2/2] iommu/arm-smmu-qcom: Move the adreno smmu specific impl earlier
From: Bjorn Andersson
Date: Fri Feb 26 2021 - 12:25:40 EST
On Fri 26 Feb 03:55 CST 2021, Sai Prakash Ranjan wrote:
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Adreno(GPU) SMMU and APSS(Application Processor SubSystem) SMMU
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both implement "arm,mmu-500" in some QTI SoCs and to run through
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adreno smmu specific implementation such as enabling split pagetables
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support, we need to match the "qcom,adreno-smmu" compatible first
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before apss smmu or else we will be running apps smmu implementation
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for adreno smmu and the additional features for adreno smmu is never
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set. For ex: we have "qcom,sc7280-smmu-500" compatible for both apps
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and adreno smmu implementing "arm,mmu-500", so the adreno smmu
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implementation is never reached because the current sequence checks
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for apps smmu compatible(qcom,sc7280-smmu-500) first and runs that
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specific impl and we never reach adreno smmu specific implementation.
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So you're saying that you have a single SMMU instance that's compatible
with both an entry in qcom_smmu_impl_of_match[] and "qcom,adreno-smmu"?
Per your proposed change we will pick the adreno ops _only_ for this
component, essentially disabling the non-Adreno quirks selected by the
qcom impl. As such keeping the non-adreno compatible in the
qcom_smmu_impl_init[] seems to only serve to obfuscate the situation.
Don't we somehow need the combined set of quirks? (At least if we're
running this with a standard UEFI based boot flow?)
Regards,
Bjorn
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Suggested-by: Akhil P Oommen <akhilpo@xxxxxxxxxxxxxx>
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Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
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---
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drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 12 +++++++++---
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1 file changed, 9 insertions(+), 3 deletions(-)
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diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
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index bea3ee0dabc2..03f048aebb80 100644
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--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
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+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
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@@ -345,11 +345,17 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu)
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{
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const struct device_node *np = smmu->dev->of_node;
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- if (of_match_node(qcom_smmu_impl_of_match, np))
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- return qcom_smmu_create(smmu, &qcom_smmu_impl);
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-
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+ /*
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+ * Do not change this order of implementation, i.e., first adreno
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+ * smmu impl and then apss smmu since we can have both implementing
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+ * arm,mmu-500 in which case we will miss setting adreno smmu specific
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+ * features if the order is changed.
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+ */
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if (of_device_is_compatible(np, "qcom,adreno-smmu"))
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return qcom_smmu_create(smmu, &qcom_adreno_smmu_impl);
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+ if (of_match_node(qcom_smmu_impl_of_match, np))
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+ return qcom_smmu_create(smmu, &qcom_smmu_impl);
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+
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return smmu;
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}
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--
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