Re: [PATCH 2/2] iommu/arm-smmu-qcom: Move the adreno smmu specific impl earlier

[Sai Prakash Ranjan]

On 2021-02-25 23:36, Jordan Crouse wrote:
> On Thu, Feb 25, 2021 at 03:54:10PM +0530, Sai Prakash Ranjan wrote:
> > 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@xxxxxxxxxxxxxx>
> > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > ---
> >
> > Its either this or we add a new compatible for adreno smmu 
> > implementing
> > arm,mmu-500 like "qcom,sc7280-adreno-smmu-500".
> >
> > ---
> >  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 6 +++---
> >  1 file changed, 3 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..7d0fc2c8e72f 100644
> > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> > @@ -345,11 +345,11 @@ 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);
> > -
> >  	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);
> > +
>
> It would be good to add a comment here explaining the order here so we
> don't accidentally reorganize ourselves back into a problem later.

Sure its better, will add it.

Thanks,
Sai

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