21.08.2020 03:28, Robin Murphy пишет: ... >> Will a returned NULL tell to IOMMU core that implicit domain shouldn't >> be used? Is it possible to leave this driver as-is? > > The aim of this patch was just to make the conversion without functional > changes wherever possible, i.e. maintain an equivalent to the existing > ARM behaviour of allocating its own implicit domains for everything. It > doesn't represent any judgement of whether that was ever appropriate for > this driver in the first place ;) > > Hopefully my other reply already covered the degree of control drivers > can have with proper default domains, but do shout if anything wasn't > clear. Thank you for the detailed comments! I wasn't watching closely all the recent iommu/ changes and yours clarification is very helpful! My current understanding is that the GART driver will need to support the IOMMU_DOMAIN_IDENTITY and set def_domain_type to IOMMU_DOMAIN_IDENTITY for all devices. Meanwhile, today's upstream drivers don't use GART, hence this patch should be okay. Although, it's a bit unlikely that the IOMMU_DOMAIN_DMA type will ever be useful for the GART, and thus, I'm still thinking that will be a bit nicer to keep GART driver as-is for now.
