linux-kernel - Re: [PATCH] iommu/arm-smmu-qcom: Only enable stall on smmu-v2

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Message-ID: <a15a7594-8793-478b-a86e-81a06812e4ff@quicinc.com>
Date: Tue, 17 Dec 2024 01:58:30 +0530
From: Akhil P Oommen <quic_akhilpo@...cinc.com>
To: Rob Clark <robdclark@...il.com>, <iommu@...ts.linux.dev>
CC: <linux-arm-msm@...r.kernel.org>, <freedreno@...ts.freedesktop.org>,
        Rob
 Clark <robdclark@...omium.org>, Will Deacon <will@...nel.org>,
        Robin Murphy
	<robin.murphy@....com>, Joerg Roedel <joro@...tes.org>,
        "moderated list:ARM
 SMMU DRIVERS" <linux-arm-kernel@...ts.infradead.org>,
        open list
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iommu/arm-smmu-qcom: Only enable stall on smmu-v2

On 12/16/2024 10:40 PM, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> On mmu-500, stall-on-fault seems to stall all context banks, causing the
> GMU to misbehave.  So limit this feature to smmu-v2 for now.
> 
> This fixes an issue with an older mesa bug taking outo the system
> because of GMU going off into the year.
> 
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index c4c52f7bd09a..1c881e88fc4d 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -331,8 +331,10 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>  	priv->get_ttbr1_cfg = qcom_adreno_smmu_get_ttbr1_cfg;
>  	priv->set_ttbr0_cfg = qcom_adreno_smmu_set_ttbr0_cfg;
>  	priv->get_fault_info = qcom_adreno_smmu_get_fault_info;
> -	priv->set_stall = qcom_adreno_smmu_set_stall;
> -	priv->resume_translation = qcom_adreno_smmu_resume_translation;
> +	if (of_device_is_compatible(np, "qcom,smmu-v2")) {
> +		priv->set_stall = qcom_adreno_smmu_set_stall;
> +		priv->resume_translation = qcom_adreno_smmu_resume_translation;
> +	}

Shall we disable this from the driver instead? A debugfs knob to trigger
coredump after a pagefault is very convenient.

-Akhil

>  	priv->set_prr_bit = NULL;
>  	priv->set_prr_addr = NULL;
>