Messages in this thread | | | Date | Thu, 27 Feb 2020 14:21:37 +0100 | From | Gerd Hoffmann <> | Subject | Re: [PATCH v5 1/3] drm/shmem: add support for per object caching flags. |
| |
Hi,
> > So I'd like to push patches 1+2 to -fixes and sort everything else later > > in -next. OK? > > OK with me.
Done.
>> [ context: why shmem helpers use pgprot_writecombine + pgprot_decrypted? >> we get conflicting mappings because of that, linear kernel >> map vs. gem object vmap/mmap ]
> Do we have any idea what drivers are actually using > write-combine and decrypted?
drivers/gpu/drm# find -name Kconfig* -print | xargs grep -l DRM_GEM_SHMEM_HELPER ./lima/Kconfig ./tiny/Kconfig ./cirrus/Kconfig ./Kconfig ./panfrost/Kconfig ./udl/Kconfig ./v3d/Kconfig ./virtio/Kconfig
virtio needs cached. cirrus+udl should be ok with cached too.
Not clue about the others (lima, tiny, panfrost, v3d). Maybe they use write-combine just because this is what they got by default from drm_gem_mmap_obj(). Maybe they actually need that. Trying to Cc: maintainters (and drop stable@).
On decrypted: I guess that is only relevant for virtual machines, i.e. virtio-gpu and cirrus?
virtio-gpu needs it, otherwise the host can't show the virtual display. cirrus bounces everything via blits to vram, so it should be ok without decrypted. I guess that implies we should make decrypted configurable.
cheers, Gerd
| |