Re: [PATCH v7 18/24] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update

Jean-Philippe Brucker
2020-09-16T14:13:20Z

On Fri, Aug 28, 2020 at 05:28:22PM +0800, Zenghui Yu wrote:
> On 2020/5/20 1:54, Jean-Philippe Brucker wrote:
> > @@ -4454,6 +4470,12 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
> > smmu->features |= ARM_SMMU_FEAT_E2H;
> > }
> > + if (reg & (IDR0_HA | IDR0_HD)) {
> > + smmu->features |= ARM_SMMU_FEAT_HA;
> > + if (reg & IDR0_HD)
> > + smmu->features |= ARM_SMMU_FEAT_HD;
> > + }
> > +
>
> nitpick:
>
> As per the IORT spec (DEN0049D, 3.1.1.2 SMMUv3 node, Table 10), the
> "HTTU Override" flag of the SMMUv3 node can override the value in
> SMMU_IDR0.HTTU. You may want to check this bit before selecting the
> {HA,HD} features and shout if there is a mismatch between firmware and
> the SMMU implementation. Just like how ARM_SMMU_FEAT_COHERENCY is
> selected.

Thanks for pointing this out, I didn't know about these flags but have
added them to the patch now.

Thanks,
Jean