ttm vs aarch64 mappings

[Dave Airlie]

Hey,

I've been playing a bit with nouveau on aarch64, and I noticed ttm
translates ttm_uncached into pgprot_noncached which uses
MT_DEVICE_nGnRnE. This is of course a device mapping which isn't
appropriate for memory.

For main memory we should be using pgprot_dmacoherent which translates
to MT_NORMAL_NC,
pgprot_writecombine also translates to MT_NORMAL_NC.

Now I'm not sure anything gets this wrong right now, (except maybe
nouveau), but I'm wondering would adding a ttm_uncached_ram caching
type and rename ttm_uncached to ttm_uncached_device, if that would be
a good idea?

Has anyone else come across this problem with TTM on aarch64? or
understand if I'm missing something.

Dave.