Messages in this thread | | | Subject | Re: [PATCH 0/5] Qcom smmu-500 TLB invalidation errata for sdm845 | From | Vivek Gautam <> | Date | Wed, 5 Sep 2018 14:52:21 +0530 |
| |
On 8/14/2018 5:54 PM, Vivek Gautam wrote: > Hi Will, > > > On 8/14/2018 5:10 PM, Will Deacon wrote: >> Hi Vivek, >> >> On Tue, Aug 14, 2018 at 04:25:23PM +0530, Vivek Gautam wrote: >>> Qcom's implementation of arm,mmu-500 on sdm845 has a >>> functional/performance >>> errata [1] because of which the TCU cache look ups are stalled during >>> invalidation cycle. This is mitigated by serializing all the >>> invalidation >>> requests coming to the smmu. >> How does this implementation differ from the one supported by >> qcom_iommu.c? >> I notice you're adding firmware hooks here, which we avoided by >> having the >> extra driver. Please help me understand which devices exist, how they >> differ, and which drivers are intended to support them! > > IIRC, the qcom_iommu driver was intended to support the static context > bank - SID > mapping, and is very specific to the smmu-v2 version present on > msm8916 soc. > However, this is the qcom's mmu-500 implementation specific errata. > qcom_iommu > will not be able to support mmu-500 configurations. > Rob Clark can add more. > Let you know what you suggest.
Rob, can you please comment about how qcom-smmu driver has different implementation from arm-smmu driver? Will, in case we would want to use arm-smmu driver, what would you suggest for having the firmware hooks? Thanks.
Best regards Vivek > >> >> Also -- you didn't CC all the maintainers for the firmware bits, so >> adding >> Andy here for that, and Rob for the previous question. > > I added Andy to the series, would you want me to add Rob H also? > > Best regards > Vivek > >> >> Thanks, >> >> Will >
| |