[PATCH v3 0/2] drm: nouveau: memory coherency for ARM

[Alexandre Courbot]

While this series is more correct from the DMA API point of view, it
is also much heavier as it strictly disables the use of any cache on
all user-space mapped BOs, and is also much more restricted in terms
of which memory it can use.

I have a v4 in the works that lets us use TTM for user-mapped objects
and only falls back to using the DMA API for kernel-only objects
(fences & PBs basically). Will push it shortly but wanted to signal
this revision as deprecated in the meantime.

On Fri, Jun 27, 2014 at 8:22 PM, Alexandre Courbot <acourbot at nvidia.com> wrote:
> v2 was doing some pretty nasty things with the DMA API, so I took a different
> approach for this v3.
>
> As suggested, this version uses ttm_dma_populate() to populate BOs. The reason
> for doing this was that it would entitle us to using the DMA sync functions,
> but since the memory returned is already coherent anyway, we do not even
> need to call these functions anymore.
>
> So this series has turned into 2 small patches:
>
> - The first attempts to make it more obvious that Nouveau can use different
> ways to populate TTs, and make it possible to choose which method to use from
> a single place.
> - The second leverages this work to select the DMA allocator to populate TTs
> on ARM.
>
> Doing this solves all our coherency problems with Nouveau on Tegra, and
> hopefully makes the code easier to read in the process.
>
> Alexandre Courbot (2):
>   drm/nouveau: cleanup TTM population logic
>   drm/nouveau: use DMA TT population method on ARM
>
>  drivers/gpu/drm/nouveau/nouveau_bo.c  | 63 ++++++++++++++++++-----------------
>  drivers/gpu/drm/nouveau/nouveau_drm.h | 11 ++++++
>  drivers/gpu/drm/nouveau/nouveau_ttm.c | 17 ++++++++++
>  3 files changed, 61 insertions(+), 30 deletions(-)
>
> --
> 2.0.0
>