On 30.07.2024 10:50 AM, Dmitry Baryshkov wrote: > On Tue, 30 Jul 2024 at 11:08, Konrad Dybcio <konradybcio@xxxxxxxxx> wrote: >> >> On 29.07.2024 11:21 PM, Dmitry Baryshkov wrote: >>> On Tue, 30 Jul 2024 at 00:08, Rob Clark <robdclark@xxxxxxxxx> wrote: >>>> >>>> On Mon, Jul 29, 2024 at 1:14 PM Dmitry Baryshkov >>>> <dmitry.baryshkov@xxxxxxxxxx> wrote: >>>>> >>>>> On Mon, Jul 29, 2024 at 10:37:48AM GMT, Konrad Dybcio wrote: >>>>>> From: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> >>>>>> >>>>>> SDM845's Adreno SMMU is unique in that it actually advertizes support >>>>>> for 16K (and 32M) pages, which doesn't hold for newer SoCs. >>>>>> >>>>>> This however, seems either broken in the hardware implementation, the >>>>>> hypervisor middleware that abstracts the SMMU, or there's a bug in the >>>>>> Linux kernel somewhere down the line that nobody managed to track down. >>>>>> >>>>>> Booting SDM845 with 16K page sizes and drm/msm results in: >>>>>> >>>>>> *** gpu fault: ttbr0=0000000000000000 iova=000100000000c000 dir=READ >>>>>> type=TRANSLATION source=CP (0,0,0,0) >>>>>> >>>>>> right after loading the firmware. The GPU then starts spitting out >>>>>> illegal intstruction errors, as it's quite obvious that it got a >>>>>> bogus pointer. >>>>>> >>>>>> Hide 16K support on SDM845's Adreno SMMU to work around this. >>>>>> >>>>>> Reported-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx> >>>>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> >>>>>> --- >>>>>> There's a mismatch in sender/committer addresses but that's "fine": >>>>>> https://lore.kernel.org/linux-usb/2024072734-scenic-unwilling-71ea@gregkh/ >>>>>> --- >>>>>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 10 ++++++++++ >>>>>> 1 file changed, 10 insertions(+) >>>>>> >>>>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c >>>>>> index 36c6b36ad4ff..d25825c05817 100644 >>>>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c >>>>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c >>>>>> @@ -338,6 +338,15 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu) >>>>>> return 0; >>>>>> } >>>>>> >>>>>> +static int qcom_adreno_smmuv2_cfg_probe(struct arm_smmu_device *smmu) >>>>>> +{ >>>>>> + /* SDM845 Adreno SMMU advertizes 16K pages support, but something is broken */ >>>>>> + if (of_device_is_compatible(smmu->dev->of_node, "qcom,sdm845-smmu-v2")) >>>>>> + smmu->features &= ~ARM_SMMU_FEAT_FMT_AARCH64_16K; >>>>> >>>>> Shouldn't we hide that uncoditionally as it's likely that none of v2 >>>>> Adreno SMMUs support 16k pages? >>>> >>>> Hmm, that would be unfortunate to have the GPU not supporting the CPU >>>> page size. I guess we could still map 16k pages as multiple 4k pages, >>>> but that is a bit sad.. >>> >>> For now this might be limited to older platforms (v2 vs -500) >> >> In the commit message: >> >>>>>> SDM845's Adreno SMMU is unique in that it actually advertizes support >>>>>> for 16K (and 32M) pages, which doesn't hold for newer SoCs. > > My question is about forbidding 16k pages for sdm845 only or for other > chips too. I'd assume that it shouldn't also work for other smmu-v2 > platforms. I'd say we shouldn't cause trouble unless we know it's an issue Konrad
