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

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

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
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