Hi Bjorn, On Mon, Sep 10, 2018 at 4:08 PM Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx> wrote: > > +linux-arm-msm > > > On 09/10/2018 11:55 AM, 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. > > > > This patch series addresses this errata by adding new tlb_ops for > > qcom,sdm845-smmu-500 [2]. These ops take context bank locks for all the > > tlb_ops that queue and sync the TLB invalidation requests. > > > > Besides adding locks, there's a way to expadite these TLB invalidations > > for display and camera devices by turning off the 'wait-for-safe' logic > > in hardware that holds the tlb invalidations until a safe level. > > This 'wait-for-safe' logic is controlled by toggling a chicken bit > > through a secure register. This secure register is accessed by making an > > explicit SCM call into the EL3 firmware. > > There are two ways of handling this logic - > > * Firmware, such as tz present on sdm845-mtp devices has a handler to do > > all the register access and bit set/clear. So is the handling in > > downstream arm-smmu driver [3]. > > * Other firmwares can have handlers to just read/write this secure > > register. In such cases the kernel make io_read/writel scm calls to > > modify the register. > > This patch series adds APIs in qcom-scm driver to handle both of these > > cases. > > > > Lastly, since these TLB invalidations can happen in atomic contexts > > there's a need to add atomic versions of qcom_scm_io_readl/writel() and > > qcom_scm_call() APIs. The traditional scm calls take mutex and we therefore > > can't use these calls in atomic contexts. > > > > This patch series is adapted version of how the errata is handled in > > downstream [1]. Gentle ping. Please let me know if you have comments on the SCM pieces in this series. Thanks & Regards Vivek > > > > Changes since v1: > > * Addressed Will and Robin's comments: > > - Dropped the patch[4] that forked out __arm_smmu_tlb_inv_range_nosync(), > > and __arm_smmu_tlb_sync(). > > - Cleaned up the errata patch further to use downstream polling mechanism > > for tlb sync. > > * No change in SCM call patches - patches 1 to 3. > > > > [1] https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/iommu/arm-smmu.c?h=msm-4.9#n4842 > > [2] https://lore.kernel.org/patchwork/patch/974114/ > > [3] https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/iommu/arm-smmu.c?h=msm-4.9#n4864 > > [4] https://patchwork.kernel.org/patch/10565349/ > > > > Vivek Gautam (4): > > firmware: qcom_scm-64: Add atomic version of qcom_scm_call > > firmware/qcom_scm: Add atomic version of io read/write APIs > > firmware/qcom_scm: Add scm call to handle smmu errata > > iommu/arm-smmu: Add support to handle Qcom's TLBI serialization errata > > > > drivers/firmware/qcom_scm-32.c | 17 ++++ > > drivers/firmware/qcom_scm-64.c | 181 +++++++++++++++++++++++++++++++---------- > > drivers/firmware/qcom_scm.c | 18 ++++ > > drivers/firmware/qcom_scm.h | 9 ++ > > drivers/iommu/arm-smmu-regs.h | 2 + > > drivers/iommu/arm-smmu.c | 133 +++++++++++++++++++++++++++++- > > include/linux/qcom_scm.h | 6 ++ > > 7 files changed, 320 insertions(+), 46 deletions(-) > > > > -- > The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > a Linux Foundation Collaborative Project > > _______________________________________________ > iommu mailing list > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linuxfoundation.org/mailman/listinfo/iommu -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
