Re: [PATCH 18/19] iommu/arm-smmu: add a way for implementations to influence SCTLR

Bjorn Andersson
2020-09-01T05:31:53Z

On Thu 13 Aug 21:41 CDT 2020, Rob Clark wrote:

> From: Rob Clark <robdclark@chromium.org>
>
> For the Adreno GPU's SMMU, we want SCTLR.HUPCF set to ensure that
> pending translations are not terminated on iova fault. Otherwise
> a terminated CP read could hang the GPU by returning invalid
> command-stream data.
>

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

> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 6 ++++++
> drivers/iommu/arm/arm-smmu/arm-smmu.c | 3 +++
> drivers/iommu/arm/arm-smmu/arm-smmu.h | 3 +++
> 3 files changed, 12 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 5640d9960610..2aa6249050ff 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -127,6 +127,12 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> (smmu_domain->cfg.fmt == ARM_SMMU_CTX_FMT_AARCH64))
> pgtbl_cfg->quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1;
>
> + /*
> + * On the GPU device we want to process subsequent transactions after a
> + * fault to keep the GPU from hanging
> + */
> + smmu_domain->cfg.sctlr_set |= ARM_SMMU_SCTLR_HUPCF;
> +
> /*
> * Initialize private interface with GPU:
> */
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index e63a480d7f71..bbec5793faf8 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -617,6 +617,9 @@ void arm_smmu_write_context_bank(struct arm_smmu_device *smmu, int idx)
> if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
> reg |= ARM_SMMU_SCTLR_E;
>
> + reg |= cfg->sctlr_set;
> + reg &= ~cfg->sctlr_clr;
> +
> arm_smmu_cb_write(smmu, idx, ARM_SMMU_CB_SCTLR, reg);
> }
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index cd75a33967bb..2df3a70a8a41 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -144,6 +144,7 @@ enum arm_smmu_cbar_type {
> #define ARM_SMMU_CB_SCTLR 0x0
> #define ARM_SMMU_SCTLR_S1_ASIDPNE BIT(12)
> #define ARM_SMMU_SCTLR_CFCFG BIT(7)
> +#define ARM_SMMU_SCTLR_HUPCF BIT(8)
> #define ARM_SMMU_SCTLR_CFIE BIT(6)
> #define ARM_SMMU_SCTLR_CFRE BIT(5)
> #define ARM_SMMU_SCTLR_E BIT(4)
> @@ -341,6 +342,8 @@ struct arm_smmu_cfg {
> u16 asid;
> u16 vmid;
> };
> + u32 sctlr_set; /* extra bits to set in SCTLR */
> + u32 sctlr_clr; /* bits to mask in SCTLR */
> enum arm_smmu_cbar_type cbar;
> enum arm_smmu_context_fmt fmt;
> };
> --
> 2.26.2
>