On Mon, Jul 10, 2023 at 03:40:28PM -0300, Jason Gunthorpe wrote: > On Mon, Jul 10, 2023 at 11:22:52AM +0300, Stanimir Varbanov wrote: > > Add def_domain_type implementation op and override default IOMMU > > domain Kconfig option (CONFIG_IOMMU_DEFAULT_PASSTHROUGH=y), which > > could be enabled on some distros. The current quirk has been done > > for Tegra234 machine, because I found the issue on it. The issue > > itself appears on USB host controller which cannot be initialized > > without IOMMU translation. Something more, we proved that IOMMU > > translation is needed for display and GPU drivers as well. > > Generically, if you find HW combinations where certain end points > cannot work with passthrough (which is really weird in the first > place) it should be narrowly quirked - not just an entire platform. > > Also we don't really have a way to force non-passthrough, ARM32 > systems will always run in passthrough, for instance. Broadly the > kernel expects it to work. As I mentioned in my other, lengthy reply, passthrough is a very undesirable configuration on more recent Tegra (Tegra186 and later at least). Passthrough support (or more generally non-SMMU support) is in a sad state at the moment because we rarely ever test it. I don't think it can't be fixed, but it's going to take a bit of effort and is likely to regress again in the future if we don't keep testing it continuously. Thierry
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