linux-kernel - Re: [PATCH 1/2] iommu/arm-smmu-qcom: Fix missing adreno

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Message-ID: <7e82919d-2cfc-67e0-f096-026b259d1960@linaro.org>
Date:   Thu, 4 May 2023 21:24:08 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Rob Clark <robdclark@...il.com>,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     dri-devel@...ts.freedesktop.org, iommu@...ts.linux-foundation.org,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Sai Prakash Ranjan <quic_saipraka@...cinc.com>,
        Bjorn Andersson <quic_bjorande@...cinc.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        "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 1/2] iommu/arm-smmu-qcom: Fix missing adreno_smmu's

On 04/05/2023 21:08, Rob Clark wrote:
> On Thu, May 4, 2023 at 10:41 AM Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>>
>>
>>
>> On 2.05.2023 18:09, Rob Clark wrote:
>>> From: Rob Clark <robdclark@...omium.org>
>>>
>>> When the special handling of qcom,adreno-smmu was moved into
>>> qcom_smmu_create(), it was overlooked that we didn't have all the
>>> required entries in qcom_smmu_impl_of_match.  So we stopped getting
>>> adreno_smmu_priv on sc7180, breaking per-process pgtables.
>>>
>>> Fixes: 30b912a03d91 ("iommu/arm-smmu-qcom: Move the qcom,adreno-smmu check into qcom_smmu_create")
>>> Signed-off-by: Rob Clark <robdclark@...omium.org>
>>> ---
>> I believe the issue here is the lack of qcom,sc7180-smmu-v2 instead.
>>
>> qcom,adreno-smmu does not have to imply the "qcom smmu v2" impl
> 
> Yes, but the ordering after "qcom,smmu-500" does.  Currently we just
> need the one missing "qcom,sc7180-smmu-v2" but that seemed kind of
> fragile to me, which is why I went with "qcom,adreno-smmu" as a
> catch-all

I think, the order is not relevant when comparing compatible entries, 
see __of_match_node(). It uses scoring and the more specific compatible 
wins. This way, "qcom,adreno-smmu", "qcom,smmu-500" will always end up 
with the v2 ops instead smmu500. It was not included into the list 
intentionally, rather than being by omission.

Thus I'd also suggest adding "qcom,sc7180-smmu-v2" to the list, as we 
currently do for all SMMU_v2 devices.

> 
> BR,
> -R
> 
>>
>> Konrad
>>>   drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 5 +++++
>>>   1 file changed, 5 insertions(+)
>>>
>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>>> index d1b296b95c86..88c89424485b 100644
>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>>> @@ -512,20 +512,25 @@ static const struct of_device_id __maybe_unused qcom_smmu_impl_of_match[] = {
>>>        { .compatible = "qcom,sm6115-smmu-500", .data = &qcom_smmu_500_impl0_data},
>>>        { .compatible = "qcom,sm6125-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,sm6350-smmu-v2", .data = &qcom_smmu_v2_data },
>>>        { .compatible = "qcom,sm6350-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,sm6375-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,sm8150-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,sm8250-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,sm8350-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,sm8450-smmu-500", .data = &qcom_smmu_500_impl0_data },
>>>        { .compatible = "qcom,smmu-500", .data = &qcom_smmu_500_impl0_data },
>>> +     /*
>>> +      * Should come after the qcom,smmu-500 fallback so smmu-500 variants of
>>> +      * adreno-smmu get qcom_adreno_smmu_500_impl:
>>> +      */
>>> +     { .compatible = "qcom,adreno-smmu", .data = &qcom_smmu_v2_data },
>>>        { }
>>>   };
>>>
>>>   #ifdef CONFIG_ACPI
>>>   static struct acpi_platform_list qcom_acpi_platlist[] = {
>>>        { "LENOVO", "CB-01   ", 0x8180, ACPI_SIG_IORT, equal, "QCOM SMMU" },
>>>        { "QCOM  ", "QCOMEDK2", 0x8180, ACPI_SIG_IORT, equal, "QCOM SMMU" },
>>>        { }
>>>   };
>>>   #endif

-- 
With best wishes
Dmitry