diff options
| author | Alexandre Courbot <acourbot@nvidia.com> | 2015-02-26 12:44:51 +0900 |
|---|---|---|
| committer | Ben Skeggs <bskeggs@redhat.com> | 2015-04-14 17:00:46 +1000 |
| commit | 996f545fbb0dc9ed4a640b5ef098f51fe28cca5c (patch) | |
| tree | 4ef34ade7df6490c03202d0021b7a96581f9724d /drivers/gpu | |
| parent | a7f6da6e758cd99fcae918b63549273893983189 (diff) | |
drm/nouveau/gem: allow user-space to specify an object should be coherent
User-space use mappable BOs notably for fences, and expects that a
value update by the GPU will be immediatly visible through the
user-space mapping.
ARM has a property that may prevent this from happening though: memory
can be mapped multiple times only if the different mappings share the
same caching properties. However all the lowmem memory is already
identity-mapped into the kernel with cache enabled, so when user-space
requests an uncached mapping, we actually get an "undefined caching
policy" one and this has strange side-effects described on Freedesktop
bug 86690.
To prevent this from happening, allow user-space to explicitly specify
which objects should be coherent, and create such objects with the
TTM_PL_FLAG_UNCACHED flag. This will make TTM allocate memory using the
DMA API, which will fix the identify mapping and allow us to safely map
the objects to user-space uncached.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/nouveau/nouveau_gem.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c index 7c077fced1d1..0e690bf19fc9 100644 --- a/drivers/gpu/drm/nouveau/nouveau_gem.c +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c @@ -189,6 +189,9 @@ nouveau_gem_new(struct drm_device *dev, int size, int align, uint32_t domain, if (!flags || domain & NOUVEAU_GEM_DOMAIN_CPU) flags |= TTM_PL_FLAG_SYSTEM; + if (domain & NOUVEAU_GEM_DOMAIN_COHERENT) + flags |= TTM_PL_FLAG_UNCACHED; + ret = nouveau_bo_new(dev, size, align, flags, tile_mode, tile_flags, NULL, NULL, pnvbo); if (ret) |