Re: [PATCH V2 net 1/9] net: hns3: default enable tx bounce buffer when smmu enabled

[Paolo Abeni]

On 10/18/24 12:10, Jijie Shao wrote:
> From: Peiyang Wang <wangpeiyang1@xxxxxxxxxx>
> 
> The SMMU engine on HIP09 chip has a hardware issue.
> SMMU pagetable prefetch features may prefetch and use a invalid PTE
> even the PTE is valid at that time. This will cause the device trigger
> fake pagefaults. The solution is to avoid prefetching by adding a
> SYNC command when smmu mapping a iova. But the performance of nic has a
> sharp drop. Then we do this workaround, always enable tx bounce buffer,
> avoid mapping/unmapping on TX path.
> 
> This issue only affects HNS3, so we always enable
> tx bounce buffer when smmu enabled to improve performance.
> 
> Signed-off-by: Peiyang Wang <wangpeiyang1@xxxxxxxxxx>
> Signed-off-by: Jian Shen <shenjian15@xxxxxxxxxx>
> Signed-off-by: Jijie Shao <shaojijie@xxxxxxxxxx>

I'm sorry to nick pick on somewhat small details, but we really need a
fixes tag here to make 110% clear is a bugfix. I guess it could be the
commit introducing the support for the buggy H/W.

Thanks,

Paolo