Re: [PATCH v2 3/8] iommu/arm-smmu: Add definition for ARM_SMMU_CB_FSRRESTORE

[AngeloGioacchino Del Regno]

Il 11/11/22 16:18, Robin Murphy ha scritto:
> On 11/11/2022 2:59 pm, AngeloGioacchino Del Regno wrote:
> > In preparation for adding a proper context bank reset sequence in
> > qcom_iommu, add a definition for the implementation defined Fault
> > Status Restore register (FSRRESTORE).
>
> It's not implementation defined, it's architectural. But I don't follow why we 
> should need this. If we're resetting FSR, we don't need to restore any previous 
> value to it; all we want to do is clear it, which we do already via its own mechanism.

The spec says "configurations" -> implementation defined whether the system
implements stage 1 translation.... and that's how I got confused about it, sorry.

Thanks for the review, this clears up my doubts: I can reset FSR without caring
about FSRRESTORE.
I'll send a v3 ASAP.

Regards,
Angelo

> Thanks,
> Robin.
>
> > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > ---
> >   drivers/iommu/arm/arm-smmu/arm-smmu.h | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h 
> > b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > index 703fd5817ec1..5015138799c5 100644
> > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > @@ -219,6 +219,7 @@ enum arm_smmu_cbar_type {
> >                        ARM_SMMU_FSR_TF |        \
> >                        ARM_SMMU_FSR_IGN)
> > +#define ARM_SMMU_CB_FSRRESTORE        0x5c
> >   #define ARM_SMMU_CB_FAR            0x60
> >   #define ARM_SMMU_CB_FSYNR0        0x68