Re: [PATCH 1/2] iommu/arm-smmu-qcom: Skip the TTBR1 quirk for db820c.

Bjorn Andersson
2021-03-30T03:23:38Z

On Fri 26 Mar 18:13 CDT 2021, Eric Anholt wrote:

> db820c wants to use the qcom smmu path to get HUPCF set (which keeps
> the GPU from wedging and then sometimes wedging the kernel after a
> page fault), but it doesn't have separate pagetables support yet in
> drm/msm so we can't go all the way to the TTBR1 path.
>
> Signed-off-by: Eric Anholt <eric@anholt.net>

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> ---
>
> We've been seeing a flaky test per day or so in Mesa CI where the
> kernel gets wedged after an iommu fault turns into CP errors. With
> this patch, the CI isn't throwing the string of CP errors on the
> faults in any of the ~10 jobs I've run so far.
>
> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index bcda17012aee..51f22193e456 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -130,6 +130,16 @@ static int qcom_adreno_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_doma
> return __arm_smmu_alloc_bitmap(smmu->context_map, start, count);
> }
>
> +static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu)
> +{
> + const struct device_node *np = smmu->dev->of_node;
> +
> + if (of_device_is_compatible(np, "qcom,msm8996-smmu-v2"))
> + return false;
> +
> + return true;
> +}
> +
> static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
> {
> @@ -144,7 +154,8 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> * be AARCH64 stage 1 but double check because the arm-smmu code assumes
> * that is the case when the TTBR1 quirk is enabled
> */
> - if ((smmu_domain->stage == ARM_SMMU_DOMAIN_S1) &&
> + if (qcom_adreno_can_do_ttbr1(smmu_domain->smmu) &&
> + (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) &&
> (smmu_domain->cfg.fmt == ARM_SMMU_CTX_FMT_AARCH64))
> pgtbl_cfg->quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1;
>
> --
> 2.31.0
>