Hi Julien, > On 18 Apr 2021, at 6:48 pm, Julien Grall <jul...@xen.org> wrote: > > > > On 16/04/2021 17:41, Rahul Singh wrote: >> Hi Julien > > Hi Rahul, > >>> On 16 Apr 2021, at 5:08 pm, Julien Grall <jul...@xen.org> wrote: >>> >>> >>> >>> On 16/04/2021 17:05, Rahul Singh wrote: >>>>> On 16 Apr 2021, at 4:23 pm, Julien Grall <jul...@xen.org> wrote: >>>>> >>>>> >>>>> >>>>> On 16/04/2021 16:01, Rahul Singh wrote: >>>>>> Hi Julien, >>>>> >>>>> Hi Rahul, >>>>> >>>>>>> On 16 Apr 2021, at 3:35 pm, Julien Grall <jul...@xen.org> wrote: >>>>>>> >>>>>>> Hi, >>>>>>> >>>>>>> On 16/04/2021 12:25, Rahul Singh wrote: >>>>>>>> Revert the code that associates the group pointer with the S2CR as this >>>>>>>> code causing an issue when the SMMU device has more than one master >>>>>>>> device. >>>>>>> >>>>>>> It is not clear to me why this change was first added. Are we missing >>>>>>> any feature when reverting it? >>>>>> This feature was added when we backported the code from Linux to fix the >>>>>> stream match conflict issue >>>>>> as part of commit "xen/arm: smmuv1: Intelligent SMR allocation”. >>>>>> This is an extra feature added to allocate IOMMU group based on >>>>>> stream-id. If two device has the >>>>>> same stream-id then we assign those devices to the same group. >>>>> >>>>> If we revert the patch, then it would not be possible to use the SMMU if >>>>> two devices use the same stream-id. Is that correct? >>>> No. If we revert the patch we can use the SMMU if two devices use the same >>>> stream-id without any issue but each device will be in a separate >>>> group.This is same behaviour before the code is merged. >>> >>> Ok. So there is no change in behavior. Good. Can you propose a commit >>> message clarifying that? >> Please have a look if it make sense. >> xen/arm: smmuv1: Revert associating the group pointer with the S2CR >> Revert the code that associates the group pointer with the S2CR as this >> code causing an issue when the SMMU device has more than one master >> device with same stream-id. This issue is introduced by the below commit: >> “0435784cc75dcfef3b5f59c29deb1dbb84265ddb:xen/arm: smmuv1: Intelligent SMR >> allocation” >> Reverting the code will not impact to use of SMMU if two devices use the >> same stream-id but each device will be in a separate group. This is the same >> behaviour before the code is merged. > > Look good to me. Is this patch to be applied on top of Stefano's series? If > not, is there going to be more clash? >
As per Stefano's mail he already tested his patch series on top of this patch. I think this patch has to merged before Stefano’s patch series Let Stefano also confirm that. I think there will be no more clashes. Regards, Rahul > Cheers, > > -- > Julien Grall
