linux-kernel - Re: [PATCHv3 4/6] iommu/arm-smmu-qcom: Request direct mapping for modem device

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Date:   Mon, 20 Apr 2020 18:09:32 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Will Deacon <will@...nel.org>, Joerg Roedel <joro@...tes.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Rob Clark <robdclark@...il.com>
Cc:     Stephen Boyd <swboyd@...omium.org>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Matthias Kaehlcke <mka@...omium.org>,
        Evan Green <evgreen@...omium.org>
Subject: Re: [PATCHv3 4/6] iommu/arm-smmu-qcom: Request direct mapping for
 modem device

On 2020-04-20 5:42 pm, Sai Prakash Ranjan wrote:
> From: Sibi Sankar <sibis@...eaurora.org>
> 
> Request direct mapping for modem on platforms which don't have TrustZone
> (which programs the modem SIDs) to prevent the following global faults seen
> on Cheza/Trogdor:

Not strictly true - it's patch #6/6 that prevents *those* faults (and 
these days the driver should be reporting unmatched streams a little 
more helpfully). This change would resolve the context faults and/or 
weird memory corruption that might result from applying patch #6 alone - 
this is the crazy thing where transactions sometimes go directly to DRAM 
round the side of the SMMU so we can never safely remap anything, right?

Robin.

> arm-smmu 15000000.iommu: Unexpected global fault, this could be serious
> arm-smmu 15000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000000,
> 			 GFSYNR1 0x00000781, GFSYNR2 0x00000000
> 
> arm-smmu 15000000.iommu: Unexpected global fault, this could be serious
> arm-smmu 15000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000000,
> 			 GFSYNR1 0x00000461, GFSYNR2 0x00000000
> 
> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
> ---
>   drivers/iommu/arm-smmu-qcom.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c
> index 5bedf21587a5..cf01d0215a39 100644
> --- a/drivers/iommu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm-smmu-qcom.c
> @@ -17,7 +17,9 @@ static const struct of_device_id qcom_smmu_client_of_match[] = {
>   	{ .compatible = "qcom,mdp4" },
>   	{ .compatible = "qcom,mdss" },
>   	{ .compatible = "qcom,sc7180-mdss" },
> +	{ .compatible = "qcom,sc7180-mss-pil" },
>   	{ .compatible = "qcom,sdm845-mdss" },
> +	{ .compatible = "qcom,sdm845-mss-pil" },
>   	{ }
>   };
>   
>