Hi Julien, > On 20 Apr 2021, at 1:39 pm, Julien Grall <jul...@xen.org> wrote: > > Hi, > > On 19/04/2021 17:21, Stefano Stabellini wrote: >> On Mon, 19 Apr 2021, Rahul Singh wrote: >>> 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. >> Yes, this patch is to be committed *before* my series and I have already >> tested this patch alone and with my series on top. Both cases work fine. > > Cool. Thanks for the confirmation. I have committed the patch with the new > commit message (although, I tweaked a little bit to use the abbreviated > version of the commit ID). >
Thanks! Regards, Rahul > Cheers, > > -- > Julien Grall
