[RFC 1/2] iommu/arm-smmu-v3: Remove bypass in arm_smmu_reset_device

Yisheng Xie xieyisheng1 at huawei.com
Tue Apr 24 04:57:06 PDT 2018


Hi Robin,

Thanks for your comment!
On 2018/4/24 0:07, Robin Murphy wrote:
> On 23/04/18 12:45, Yisheng Xie wrote:
>> Add a bypass parameter in arm_smmu_device to keep whether smmu device
>> should pypass or not, so parameter bypass in arm_smmu_reset_device can
>> be removed.
> 
> Given that the GBPA configuration implied by the bypass argument here
> is only there to avoid initialising a full stream table when the firmware
> is terminally broken, I wonder if it would make sense to simply skip
> allocating a stream table at all in that case. Then we could just base
> the subsequent SMMUEN/GPBA decision on whether strtab_cfg.strtab is valid or not.
> 
Yes, it may save many memory, and should be care about not access strtab when attach
device or other similar scenario, anyway software can achieve this after move bypass
to struct arm_smmu_device.

Thanks
Yisheng
> Robin.
> 




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