On 06/06/2017 12:11 PM, Jean-Philippe Brucker wrote: > On 05/06/17 18:20, Rob Herring wrote: >> pci-host-{e,}cam-generic is a special case. I'm okay with having a >> property for that I suppose. We should not require this property though >> and allow for it to be implied by the SoC specific compatible as well. > > The property isn't useful for host-generic since a host like Qemu can > easily disable ATS in the IOMMU. It would only be here for consistency. > Changing IOMMU registers wouldn't be as simple for a firmware running on > real hardware. Sorry I was mistaken here. AMD Seattle hardware, for instance, implements a pure host-ecam-generic. So it's not exclusively used by Qemu. A quick search in the kernel also brings up alpine and thunder2. So I guess I'll move ats-supported documentation to host-generic-pci.txt. Thanks, Jean