On Thu, Mar 25, 2021 at 01:10:12PM +0530, Sai Prakash Ranjan wrote: > On 2021-03-15 00:31, Sai Prakash Ranjan wrote: > > On 2021-03-12 04:59, Bjorn Andersson wrote: > > > On Sat 27 Feb 07:53 CST 2021, Sai Prakash Ranjan wrote: > > > > On 2021-02-27 00:44, Bjorn Andersson wrote: > > > > > On Fri 26 Feb 12:23 CST 2021, Rob Clark wrote: > > > > > > > > > > > > > > > The current logic picks one of: > > > > > 1) is the compatible mentioned in qcom_smmu_impl_of_match[] > > > > > 2) is the compatible an adreno > > > > > 3) no quirks needed > > > > > > > > > > The change flips the order of these, so the only way I can see this > > > > > change affecting things is if we expected a match on #2, but we got > > > > > one > > > > > on #1. > > > > > > > > > > Which implies that the instance that we want to act according to the > > > > > adreno impl was listed in qcom_smmu_impl_of_match[] - which either is > > > > > wrong, or there's a single instance that needs both behaviors. > > > > > > > > > > (And I believe Jordan's answer confirms the latter - there's a single > > > > > SMMU instance that needs all them quirks at once) > > > > > > > > > > > > > Let me go through the problem statement in case my commit > > > > message wasn't > > > > clear. There are two SMMUs (APSS and GPU) on SC7280 and both are > > > > SMMU500 > > > > (ARM SMMU IP). > > > > > > > > APSS SMMU compatible - ("qcom,sc7280-smmu-500", "arm,mmu-500") > > > > GPU SMMU compatible - ("qcom,sc7280-smmu-500", > > > > "qcom,adreno-smmu", "arm,mmu-500") > > > > > > > > Now if we take SC7180 as an example, GPU SMMU was QSMMU(QCOM SMMU IP) > > > > and APSS SMMU was SMMU500(ARM SMMU IP). > > > > > > > > APSS SMMU compatible - ("qcom,sc7180-smmu-500", "arm,mmu-500") > > > > GPU SMMU compatible - ("qcom,sc7180-smmu-v2", > > > > "qcom,adreno-smmu", "qcom,smmu-v2") > > > > > > > > Current code sequence without this patch, > > > > > > > > if (of_match_node(qcom_smmu_impl_of_match, np)) > > > > return qcom_smmu_create(smmu, &qcom_smmu_impl); > > > > > > > > if (of_device_is_compatible(np, "qcom,adreno-smmu")) > > > > return qcom_smmu_create(smmu, &qcom_adreno_smmu_impl); > > > > > > > > Now if we look at the compatible for SC7180, there is no problem > > > > because > > > > the APSS SMMU will match the one in qcom_smmu_impl_of_match[] > > > > and GPU SMMU > > > > will match "qcom,adreno-smmu" because the compatible strings are > > > > different. > > > > But for SC7280, both the APSS SMMU and GPU SMMU > > > > compatible("qcom,sc7280-smmu-500") > > > > are same. So GPU SMMU will match with the one in > > > > qcom_smmu_impl_of_match[] > > > > i.e.., "qcom,sc7280-smmu-500" which functionally doesn't cause > > > > any problem > > > > but we will miss settings for split pagetables which are part of > > > > GPU SMMU > > > > specific implementation. > > > > > > > > We can avoid this with yet another new compatible for GPU SMMU > > > > something like > > > > "qcom,sc7280-adreno-smmu-500" but since we can handle this > > > > easily in the > > > > driver and since the IPs are same, meaning if there was a > > > > hardware quirk > > > > required, then we would need to apply to both of them and would > > > > this additional > > > > compatible be of any help? > > > > > > > > > > No, I think you're doing the right thing of having them both. I just > > > didn't remember us doing that. > > > > > > > Coming to the part of quirks now, you are right saying both > > > > SMMUs will need > > > > to have the same quirks in SC7280 and similar others where both > > > > are based on > > > > same IPs but those should probably be *hardware quirks* and if > > > > they are > > > > software based like the S2CR quirk depending on the firmware, > > > > then it might > > > > not be applicable to both. In case if it is applicable, then as > > > > Jordan mentioned, > > > > we can add the same quirks in GPU SMMU implementation. > > > > > > > > > > I do suspect that at some point (probably sooner than later) we'd have > > > to support both inheriting of stream from the bootloader and the > > > Adreno > > > "quirks" in the same instance. > > > > > > But for now this is okay to me. > > > > > > > Sure, let me know if you or anyone face any issues without it and I will > > add it. I will resend this series with the dt-bindings patch for sc7280 > > smmu > > which wasn't cc'd to smmu folks by mistake. > > > > I think there is consensus on this series. I can resend if required but it > still applies cleanly, let me know if you have any comments?
Please resend with the bindings patch, and I'd like Bjorn's Ack as well. Will _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu