linux-kernel - Re: [PATCH v4 3/3] iommu: arm-smmu-impl: Add sdm845 implementation hook

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Date:   Fri, 06 Sep 2019 08:07:07 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>, agross@...nel.org,
        iommu@...ts.linux-foundation.org, joro@...tes.org,
        robin.murphy@....com, will.deacon@....com
Cc:     bjorn.andersson@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vivek Gautam <vivek.gautam@...eaurora.org>
Subject: Re: [PATCH v4 3/3] iommu: arm-smmu-impl: Add sdm845 implementation hook

Quoting Vivek Gautam (2019-08-22 23:32:48)
> diff --git a/drivers/iommu/arm-smmu-impl.c b/drivers/iommu/arm-smmu-impl.c
> index 3f88cd078dd5..0aef87c41f9c 100644
> --- a/drivers/iommu/arm-smmu-impl.c
> +++ b/drivers/iommu/arm-smmu-impl.c
> @@ -102,7 +103,6 @@ static struct arm_smmu_device *cavium_smmu_impl_init(struct arm_smmu_device *smm
>         return &cs->smmu;
>  }
>  
> -
>  #define ARM_MMU500_ACTLR_CPRE          (1 << 1)
>  
>  #define ARM_MMU500_ACR_CACHE_LOCK      (1 << 26)

Drop this hunk? 

> @@ -147,6 +147,28 @@ static const struct arm_smmu_impl arm_mmu500_impl = {
>         .reset = arm_mmu500_reset,
>  };
>  
> +static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
> +{
> +       int ret;
> +
> +       arm_mmu500_reset(smmu);
> +
> +       /*
> +        * To address performance degradation in non-real time clients,
> +        * such as USB and UFS, turn off wait-for-safe on sdm845 based boards,
> +        * such as MTP and db845, whose firmwares implement secure monitor
> +        * call handlers to turn on/off the wait-for-safe logic.
> +        */
> +       ret = qcom_scm_qsmmu500_wait_safe_toggle(0);
> +       if (ret)
> +               dev_warn(smmu->dev, "Failed to turn off SAFE logic\n");
> +
> +       return 0;

return ret? Or intentionally don't return an error for failure?

> +}
> +
> +const struct arm_smmu_impl qcom_sdm845_smmu500_impl = {

static?

> +       .reset = qcom_sdm845_smmu500_reset,
> +};
>  
>  struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
>  {