linux-kernel - Re: [PATCH 3/3] iommu/arm-smmu: re-enable context caching in smmu reset operation

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Message-ID: <981deaf3-c7e2-4bbc-86b8-2151bf0b6e00@quicinc.com>
Date:   Sat, 4 Nov 2023 03:36:42 +0530
From:   Bibek Kumar Patro <quic_bibekkum@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
        <a39.skl@...il.com>, <konrad.dybcio@...aro.org>,
        <quic_saipraka@...cinc.com>, <quic_pkondeti@...cinc.com>,
        <quic_molvera@...cinc.com>, <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <qipl.kernel.upstream@...cinc.com>
Subject: Re: [PATCH 3/3] iommu/arm-smmu: re-enable context caching in smmu
 reset operation



On 11/4/2023 3:28 AM, Dmitry Baryshkov wrote:
> On Fri, 3 Nov 2023 at 23:53, Bibek Kumar Patro
> <quic_bibekkum@...cinc.com> wrote:
>>
>> Context caching is re-enabled in the prefetch buffer for Qualcomm SoCs
>> through SoC specific reset ops, which is disabled in the default MMU-500
>> reset ops, but is expected for context banks using ACTLR register to
>> retain the prefetch value during reset and runtime suspend.
>>
>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
>> ---
>>   drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 26 ++++++++++++++++++----
>>   1 file changed, 22 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> index 590b7c285299..f342b4778cf1 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> @@ -457,11 +457,29 @@ static int qcom_smmu_def_domain_type(struct device *dev)
>>          return match ? IOMMU_DOMAIN_IDENTITY : 0;
>>   }
>>
>> +#define ARM_MMU500_ACTLR_CPRE          BIT(1)
>> +
>> +static int qcom_smmu500_reset(struct arm_smmu_device *smmu)
>> +{
>> +       int i;
>> +       u32 reg;
>> +
>> +       arm_mmu500_reset(smmu);
>> +
>> +               for (i = 0; i < smmu->num_context_banks; ++i) {
>> +                       reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR);
>> +                       reg |= ARM_MMU500_ACTLR_CPRE;
>> +                       arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg);
>> +               }
> 
> Wrong indentation. Did you run your patches through checkpatch.pl?
> 

Yes Dmitry, I did run checkpatch.pl script on this patch as well as 
others, got 0 errors and 0 warnings. With -f option as well. Did not
get any related errors and warnings.

>> +
>> +       return 0;
>> +}
>> +
>>   static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
>>   {
>>          int ret;
>>
>> -       arm_mmu500_reset(smmu);
>> +       qcom_smmu500_reset(smmu);
>>
>>          /*
>>           * To address performance degradation in non-real time clients,
>> @@ -488,7 +506,7 @@ static const struct arm_smmu_impl qcom_smmu_500_impl = {
>>          .init_context = qcom_smmu_init_context,
>>          .cfg_probe = qcom_smmu_cfg_probe,
>>          .def_domain_type = qcom_smmu_def_domain_type,
>> -       .reset = arm_mmu500_reset,
>> +       .reset = qcom_smmu500_reset,
>>          .write_s2cr = qcom_smmu_write_s2cr,
>>          .tlb_sync = qcom_smmu_tlb_sync,
>>   };
>> @@ -507,7 +525,7 @@ static const struct arm_smmu_impl sm8550_smmu_500_impl = {
>>          .init_context = qcom_smmu_init_context,
>>          .cfg_probe = qcom_smmu_cfg_probe,
>>          .def_domain_type = qcom_smmu_def_domain_type,
>> -       .reset = arm_mmu500_reset,
>> +       .reset = qcom_smmu500_reset,
>>          .write_s2cr = qcom_smmu_write_s2cr,
>>          .tlb_sync = qcom_smmu_tlb_sync,
>>   };
>> @@ -523,7 +541,7 @@ static const struct arm_smmu_impl qcom_adreno_smmu_v2_impl = {
>>   static const struct arm_smmu_impl qcom_adreno_smmu_500_impl = {
>>          .init_context = qcom_adreno_smmu_init_context,
>>          .def_domain_type = qcom_smmu_def_domain_type,
>> -       .reset = arm_mmu500_reset,
>> +       .reset = qcom_smmu500_reset,
>>          .alloc_context_bank = qcom_adreno_smmu_alloc_context_bank,
>>          .write_sctlr = qcom_adreno_smmu_write_sctlr,
>>          .tlb_sync = qcom_smmu_tlb_sync,
>> --
>> 2.17.1
>>
> 
>