Re: [PATCH v7 1/3] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage
On 2020-06-30 11:23, Jon Hunter wrote: On 29/06/2020 23:49, Krishna Reddy wrote: + if (!nvidia_smmu->bases[0]) + nvidia_smmu->bases[0] = smmu->base; + + return nvidia_smmu->bases[inst] + (page << smmu->pgshift); } Not critical -- just a nit: why not put the bases[0] in init()? smmu->base is not available during nvidia_smmu_impl_init() call. It is set afterwards in arm-smmu.c. It can't be avoided without changing the devm_ioremap() and impl_init() call order in arm-smmu.c. Why don't we move the call to devm_ioremap_resource() to before arm_smmu_impl_init() in arm_smmu_device_probe()? From a quick look I don't see why we cannot do this and seems better than what we are currently doing which is quite confusing and hard to understand. Yeah, I don't see any problem with adding a patch to do that. impl_init() does need to happen before generic probe starts touching any registers, but it wouldn't have any business overriding the platform resources or anything that would affect the ioremap itself. Plus it's reasonable that some theoretical future impl_init() might want to check registers for, say, a particular hardware revision, so having smmmu->base mapped and valid at that point would be no bad thing. Robin. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v7 1/3] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage
On 29/06/2020 23:49, Krishna Reddy wrote: >>> + if (!nvidia_smmu->bases[0]) >>> + nvidia_smmu->bases[0] = smmu->base; >>> + >>> + return nvidia_smmu->bases[inst] + (page << smmu->pgshift); } > >> Not critical -- just a nit: why not put the bases[0] in init()? > > smmu->base is not available during nvidia_smmu_impl_init() call. It is set > afterwards in arm-smmu.c. > It can't be avoided without changing the devm_ioremap() and impl_init() call > order in arm-smmu.c. Why don't we move the call to devm_ioremap_resource() to before arm_smmu_impl_init() in arm_smmu_device_probe()? From a quick look I don't see why we cannot do this and seems better than what we are currently doing which is quite confusing and hard to understand. Jon -- nvpublic ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v7 1/3] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage
On Mon, Jun 29, 2020 at 10:49:31PM +, Krishna Reddy wrote: > >> + if (!nvidia_smmu->bases[0]) > >> + nvidia_smmu->bases[0] = smmu->base; > >> + > >> + return nvidia_smmu->bases[inst] + (page << smmu->pgshift); } > > >Not critical -- just a nit: why not put the bases[0] in init()? > > smmu->base is not available during nvidia_smmu_impl_init() call. It is set > afterwards in arm-smmu.c. > It can't be avoided without changing the devm_ioremap() and impl_init() call > order in arm-smmu.c. I see...just checked arm_ssmu_impl_init(). ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
RE: [PATCH v7 1/3] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage
>> + if (!nvidia_smmu->bases[0]) >> + nvidia_smmu->bases[0] = smmu->base; >> + >> + return nvidia_smmu->bases[inst] + (page << smmu->pgshift); } >Not critical -- just a nit: why not put the bases[0] in init()? smmu->base is not available during nvidia_smmu_impl_init() call. It is set afterwards in arm-smmu.c. It can't be avoided without changing the devm_ioremap() and impl_init() call order in arm-smmu.c. -KR ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v7 1/3] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage
On Sun, Jun 28, 2020 at 07:28:36PM -0700, Krishna Reddy wrote:
> NVIDIA's Tegra194 SoC uses two ARM MMU-500s together to interleave
> IOVA accesses across them.
> Add NVIDIA implementation for dual ARM MMU-500s and add new compatible
> string for Tegra194 SoC SMMU topology.
>
> Signed-off-by: Krishna Reddy
> +static inline void __iomem *nvidia_smmu_page(struct arm_smmu_device *smmu,
> +unsigned int inst, int page)
> +{
> + struct nvidia_smmu *nvidia_smmu = to_nvidia_smmu(smmu);
> +
> + if (!nvidia_smmu->bases[0])
> + nvidia_smmu->bases[0] = smmu->base;
> +
> + return nvidia_smmu->bases[inst] + (page << smmu->pgshift);
> +}
Not critical -- just a nit: why not put the bases[0] in init()?
Everything else looks good to me:
Reviewed-by: Nicolin Chen
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