Subject: Re: [PATCHv2 3/6] iommu/arm-smmu: Implement iommu_ops->def_domain_type call-back

From: Sai Prakash Ranjan <[email-masked]>
Date: Mon, 20 Apr 2020 21:57:46 +0530

Hi Robin,

On 2020-04-20 20:56, Robin Murphy wrote:
> On 2020-04-20 3:37 pm, Sai Prakash Ranjan wrote:
>> Implement the new def_domain_type call-back for the ARM
>> SMMU driver. We need this to support requesting the domain
>> type by the client devices.
>> 
>> Signed-off-by: Sai Prakash Ranjan <[email-masked]>
>> ---
>>   drivers/iommu/arm-smmu.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>> 
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index e622f4e33379..b5d1d52dfbb8 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -1609,6 +1609,25 @@ static void arm_smmu_get_resv_regions(struct 
>> device *dev,
>>   	iommu_dma_get_resv_regions(dev, head);
>>   }
>>   +static int arm_smmu_def_domain_type(struct device *dev)
>> +{
>> +	struct iommu_fwspec *fwspec;
>> +	struct arm_smmu_device *smmu;
>> +
>> +	fwspec = dev_iommu_fwspec_get(dev);
>> +	if (!fwspec || fwspec->ops != &arm_smmu_ops)
>> +		return -ENODEV;
>> +
>> +	smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
>> +	if (!smmu)
>> +		return -ENODEV;
>> +
> 
> AFAICS this should only ever be called for a device in a group, which
> means an initial ->probe_device has succeeded and rather than
> defensively going the long way round, we can safely assume this:
> 
> 	struct arm_smmu_master_cfg = dev_iommu_priv_get(dev);
> 	struct arm_smmu_impl *impl = cfg->smmu->impl;
> 
> 	if (impl && impl->req_domain)
> 		return impl->req_domain(dev);
> 

Yes you are right, will use this.

Thanks,
Sai
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