On Mon, Feb 14, 2022 at 03:23:07PM +0100, Joerg Roedel wrote: > Device drivers calling into iommu_attach_device() is seldom a good > idea. In this case the sound device has some generic hardware > interface so that an existing sound driver can be re-used. Making this > driver call iommu-specific functions for some devices is something hard > to justify. Er, so this is transparent to the generic sound device? I guess something fixed up the dma_api on that device to keep working? But, then, the requirement is that nobody is using the dma API when we make this change? > With sub-groups on the other hand it would be a no-brainer, because the > sound device would be in a separate sub-group. Basically any device in > the same group as the GPU would be in a separate sub-group. I don't think it matters how big/small the group is, only that when we change the domain we know everything flowing through the domain is still happy. Jason
