On Thu, Jul 09, 2026 at 05:54:23PM +0300, Dmitry Baryshkov wrote: > On Thu, Jul 09, 2026 at 07:12:39PM +0530, Akhil P Oommen wrote: > > On 7/7/2026 10:09 PM, Dmitry Baryshkov wrote: > > > On Tue, Jul 07, 2026 at 05:02:43PM +0200, Anna Maniscalco wrote: > > >> On 7/6/26 5:04 PM, Dmitry Baryshkov wrote: > > >>> On Sun, Jul 05, 2026 at 09:13:37PM +0200, Anna Maniscalco wrote: > > >>>> In order to associate the SID used by LPAC to it's own domain and > > >>>> context bank we need a separate node on the DTS. > > >>> Can we use iommu-map instead of adding a new device using the same > > >>> addresses? You provide zero explanations, but it seems like you are > > >>> trying to separate a part of the GPU into a separate device, but it's > > >>> unnecessary. > > >> > > >> What I was trying to say is that we need to map sid0 and sid1 to > > >> different > > >> context banks. > > >> > > >> From what I recall, so long as we use the same dt node, the iommu drivert > > >> provides no way of doing this. > > >> > > >> What kgsl does is having a node for the iommu and then subnodes for gfx > > >> lpac > > >> and secure. > > >> > > >> The address on the lpac device doesn't really matter. I have very limted > > >> knowledge of DTSs but I think we could just leave it out altogether? > > > > > > I think, you were poined to the Glymur Iris patches. Another option is > > > the QDA driver being submitted too. Both ot them use iommu-map to > > > describe the same usecase - a set of SIDs which are used by the device > > > but which should not be a part of the defaut set. With it in place you > > > don't need to have separate qcom,lpac devices, no additional properties, > > > etc. > > > > > > I'd recommend following the same approach. > > > > iiuc, the conclusion in this recent thread is to use child nodes for a > > similar case: > > https://lore.kernel.org/all/[email protected]/ > > Let me check internally.
After a brief discussion: it can be either, depending on what suites better (and if you can persuade DMA / IOMMU maintainers to let one extra bus or not). -- With best wishes Dmitry
