linux-kernel - Re: [PATCH v2] iommu/arm-smmu-qcom: Add missing GMU entry to match table

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Message-ID: <86d3ee06-7c8d-4f60-bcba-80b772ec0faf@arm.com>
Date:   Mon, 11 Dec 2023 22:58:58 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Rob Clark <robdclark@...il.com>, iommu@...ts.linux-foundation.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Johan Hovold <johan@...nel.org>,
        Rob Clark <robdclark@...omium.org>, stable@...r.kernel.org,
        Will Deacon <will@...nel.org>, Joerg Roedel <joro@...tes.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Bjorn Andersson <quic_bjorande@...cinc.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Danila Tikhonov <danila@...xyga.com>,
        Elliot Berman <quic_eberman@...cinc.com>,
        "moderated list:ARM SMMU DRIVERS" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:IOMMU SUBSYSTEM" <iommu@...ts.linux.dev>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] iommu/arm-smmu-qcom: Add missing GMU entry to match
 table

On 2023-12-10 6:06 pm, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> In some cases the firmware expects cbndx 1 to be assigned to the GMU,
> so we also want the default domain for the GMU to be an identy domain.
> This way it does not get a context bank assigned.  Without this, both
> of_dma_configure() and drm/msm's iommu_domain_attach() will trigger
> allocating and configuring a context bank.  So GMU ends up attached to
> both cbndx 1 and later cbndx 2.  This arrangement seemingly confounds
> and surprises the firmware if the GPU later triggers a translation
> fault, resulting (on sc8280xp / lenovo x13s, at least) in the SMMU
> getting wedged and the GPU stuck without memory access.

Reviewed-by: Robin Murphy <robin.murphy@....com>

> Cc: stable@...r.kernel.org
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
> 
> I didn't add a fixes tag because really this issue has been there
> all along, but either didn't matter with other firmware or we didn't
> notice the problem.
> 
>   drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 549ae4dba3a6..d326fa230b96 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -243,6 +243,7 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>   
>   static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = {
>   	{ .compatible = "qcom,adreno" },
> +	{ .compatible = "qcom,adreno-gmu" },
>   	{ .compatible = "qcom,mdp4" },
>   	{ .compatible = "qcom,mdss" },
>   	{ .compatible = "qcom,sc7180-mdss" },