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Subject: Re: [PATCH v5 1/8] iommu/arm-smmu-v3: Make default domain type of
 HiSilicon PTT device to identity
To:     John Garry <john.garry@huawei.com>,
        Yicong Yang <yangyicong@hisilicon.com>,
        <gregkh@linuxfoundation.org>, <helgaas@kernel.org>,
        <alexander.shishkin@linux.intel.com>, <lorenzo.pieralisi@arm.com>,
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        <mike.leach@linaro.org>, <leo.yan@linaro.org>,
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        <robin.murphy@arm.com>, <peterz@infradead.org>, <mingo@redhat.com>,
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References: <20220308084930.5142-1-yangyicong@hisilicon.com>
 <20220308084930.5142-2-yangyicong@hisilicon.com>
 <162a116a-4b0f-c58b-6760-86d10ecf543f@huawei.com>
From:   Yicong Yang <yangyicong@huawei.com>
Message-ID: <e6d50ab3-5284-7fea-c20e-d72add9b0c82@huawei.com>
Date:   Wed, 16 Mar 2022 14:15:48 +0800
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On 2022/3/12 1:27, John Garry wrote:
> On 08/03/2022 08:49, Yicong Yang wrote:
>> The DMA of HiSilicon PTT device can only work with identical mapping.
> 
> nit: I'd have "DMA operations of the HiSilicon PTT device can only work properly with identity mappings".
> 
>> So add a quirk for the device to force the domain passthrough.
> 
> ".. domain as passthrough."
> 

thanks for the comments. will refine the commit as suggested.

>>
>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
>> ---
>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> index 6dc6d8b6b368..6f67a2b1dd27 100644
>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>> @@ -2838,6 +2838,21 @@ static int arm_smmu_dev_disable_feature(struct device *dev,
>>       }
>>   }
>>   +#define IS_HISI_PTT_DEVICE(pdev)    ((pdev)->vendor == PCI_VENDOR_ID_HUAWEI && \
>> +                     (pdev)->device == 0xa12e)
>> +
>> +static int arm_smmu_def_domain_type(struct device *dev)
>> +{
>> +    if (dev_is_pci(dev)) {
>> +        struct pci_dev *pdev = to_pci_dev(dev);
>> +
>> +        if (IS_HISI_PTT_DEVICE(pdev))
>> +            return IOMMU_DOMAIN_IDENTITY;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>   static struct iommu_ops arm_smmu_ops = {
>>       .capable        = arm_smmu_capable,
>>       .domain_alloc        = arm_smmu_domain_alloc,
>> @@ -2863,6 +2878,7 @@ static struct iommu_ops arm_smmu_ops = {
>>       .sva_unbind        = arm_smmu_sva_unbind,
>>       .sva_get_pasid        = arm_smmu_sva_get_pasid,
>>       .page_response        = arm_smmu_page_response,
>> +    .def_domain_type    = arm_smmu_def_domain_type,
>>       .pgsize_bitmap        = -1UL, /* Restricted during device attach */
>>       .owner            = THIS_MODULE,
>>   };
> 
> .