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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-25 08:48:31 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-25 08:48:31 -0700 |
commit | f98c2135f8e73f1cfba640dfb80beb0dad75f278 (patch) | |
tree | 4c97f1a81474ba6f3cb3c281685f0c79eb226859 /Documentation | |
parent | 11caf57f6a4b8e380001548b8af0a3ae3f7b4354 (diff) | |
parent | 4604202ca8d2a5e33b4bca0812b5d92975ed1bd8 (diff) | |
download | linux-f98c2135f8e73f1cfba640dfb80beb0dad75f278.tar.bz2 |
Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
Pull drm fixes from Dave Airlie:
"Just a couple of dma-buf related fixes and some amdgpu fixes, along
with a regression fix for radeon off but default feature, but makes my
30" monitor happy again"
* 'drm-next' of git://people.freedesktop.org/~airlied/linux:
drm/radeon/mst: cleanup code indentation
drm/radeon/mst: fix regression in lane/link handling.
drm/amdgpu: add invalidate_page callback for userptrs
drm/amdgpu: Revert "remove the userptr rmn->lock"
drm/amdgpu: clean up path handling for powerplay
drm/amd/powerplay: fix memory leak of tdp_table
dma-buf/fence: fix fence_is_later v2
dma-buf: Update docs for SYNC ioctl
drm: remove excess description
dma-buf, drm, ion: Propagate error code from dma_buf_start_cpu_access()
drm/atmel-hlcdc: use helper to get crtc state
drm/atomic: use helper to get crtc state
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/dma-buf-sharing.txt | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt index 32ac32e773e1..ca44c5820585 100644 --- a/Documentation/dma-buf-sharing.txt +++ b/Documentation/dma-buf-sharing.txt @@ -352,7 +352,8 @@ Being able to mmap an export dma-buf buffer object has 2 main use-cases: No special interfaces, userspace simply calls mmap on the dma-buf fd, making sure that the cache synchronization ioctl (DMA_BUF_IOCTL_SYNC) is *always* - used when the access happens. This is discussed next paragraphs. + used when the access happens. Note that DMA_BUF_IOCTL_SYNC can fail with + -EAGAIN or -EINTR, in which case it must be restarted. Some systems might need some sort of cache coherency management e.g. when CPU and GPU domains are being accessed through dma-buf at the same time. To @@ -366,10 +367,10 @@ Being able to mmap an export dma-buf buffer object has 2 main use-cases: want (with the new data being consumed by the GPU or say scanout device) - munmap once you don't need the buffer any more - Therefore, for correctness and optimal performance, systems with the memory - cache shared by the GPU and CPU i.e. the "coherent" and also the - "incoherent" are always required to use SYNC_START and SYNC_END before and - after, respectively, when accessing the mapped address. + For correctness and optimal performance, it is always required to use + SYNC_START and SYNC_END before and after, respectively, when accessing the + mapped address. Userspace cannot rely on coherent access, even when there + are systems where it just works without calling these ioctls. 2. Supporting existing mmap interfaces in importers |