linux-toradex.git/Documentation/dma-buf-sharing.txt, branch v4.9.94

dma-buf: Update docs for SYNC ioctl

2016-03-21T08:26:45+00:00

Just a bit of wording polish plus mentioning that it can fail and must
be restarted.

Requested by Sumit.

v2: Fix them typos (Hans).

Cc: Chris Wilson 
Cc: Tiago Vignatti 
Cc: Stéphane Marchesin 
Cc: David Herrmann 
Cc: Sumit Semwal 
Cc: Daniel Vetter 
CC: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: intel-gfx@lists.freedesktop.org
Cc: devel@driverdev.osuosl.org
Cc: Hans Verkuil 
Acked-by: Sumit Semwal 
Acked-by: Hans Verkuil 
Signed-off-by: Daniel Vetter

dma-buf: Add ioctls to allow userspace to flush

2016-02-12T15:01:32+00:00

The userspace 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
circumvent this problem there are begin/end coherency markers, that forward
directly to existing dma-buf device drivers vfunc hooks. Userspace can make use
of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The sequence would be
used like following:
     - mmap dma-buf fd
     - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
       to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
       want (with the new data being consumed by the GPU or say scanout device)
     - munmap once you don't need the buffer any more

v2 (Tiago): Fix header file type names (u64 -> __u64)
v3 (Tiago): Add documentation. Use enum dma_buf_sync_flags to the begin/end
dma-buf functions. Check for overflows in start/length.
v4 (Tiago): use 2d regions for sync.
v5 (Tiago): forget about 2d regions (v4); use _IOW in DMA_BUF_IOCTL_SYNC and
remove range information from struct dma_buf_sync.
v6 (Tiago): use __u64 structured padded flags instead enum. Adjust
documentation about the recommendation on using sync ioctls.
v7 (Tiago): Alex' nit on flags definition and being even more wording in the
doc about sync usage.
v9 (Tiago): remove useless is_dma_buf_file check. Fix sync.flags conditionals
and its mask order check. Add  include in dma-buf.h.

Cc: Ville Syrjälä 
Cc: David Herrmann 
Cc: Sumit Semwal 
Reviewed-by: Stéphane Marchesin 
Signed-off-by: Daniel Vetter 
Signed-off-by: Tiago Vignatti 
Reviewed-by: David Herrmann 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1455228291-29640-1-git-send-email-tiago.vignatti@intel.com

dma-buf: Remove range-based flush

2016-02-09T08:25:22+00:00

This patch removes range-based information used for optimizations in
begin_cpu_access and end_cpu_access.

We don't have any user nor implementation using range-based flush. It seems a
consensus that if we ever want something like that again (or even more robust
using 2D, 3D sub-range regions) we can use the upcoming dma-buf sync ioctl for
such.

Cc: Sumit Semwal 
Cc: Daniel Vetter 
Signed-off-by: Tiago Vignatti 
Reviewed-by: Stéphane Marchesin 
Signed-off-by: Daniel Vetter 
Link: http://patchwork.freedesktop.org/patch/msgid/1450820214-12509-3-git-send-email-tiago.vignatti@intel.com

dma-buf: cleanup dma_buf_export() to make it easily extensible

2015-04-21T09:17:16+00:00

At present, dma_buf_export() takes a series of parameters, which
makes it difficult to add any new parameters for exporters, if required.

Make it simpler by moving all these parameters into a struct, and pass
the struct * as parameter to dma_buf_export().

While at it, unite dma_buf_export_named() with dma_buf_export(), and
change all callers accordingly.

Reviewed-by: Maarten Lankhorst 
Reviewed-by: Daniel Thompson 
Acked-by: Mauro Carvalho Chehab 
Acked-by: Dave Airlie 
Signed-off-by: Sumit Semwal

Documentation/dma-buf-sharing.txt: update API descriptions

2014-08-28T06:27:24+00:00

Update some descriptions for API arguments and descriptions.

Signed-off-by: Gioh Kim 
Signed-off-by: Sumit Semwal

doc: spelling error changes

2014-05-05T13:32:05+00:00

Fixed multiple spelling errors.

Acked-by: Randy Dunlap 
Signed-off-by: Carlos E. Garcia 
Signed-off-by: Jiri Kosina

dma-buf: update exp_name when using dma_buf_export()

2014-05-05T13:28:05+00:00

commit c0b00a5 ("dma-buf: update debugfs output") modified the
default exporter name to be the KBUILD_MODNAME pre-processor
macro instead of __FILE__ but the documentation was not updated.

Also the "Supporting existing mmap interfaces in exporters" section
title seems wrong since talks about the interface used by importers.

Signed-off-by: Javier Martinez Canillas 
Reviewed-by: Daniel Vetter 
Signed-off-by: Jiri Kosina

dma-buf: Expose buffer size to userspace (v2)

2013-09-10T06:06:45+00:00

Each dma-buf has an associated size and it's reasonable for userspace
to want to know what it is.

Since userspace already has an fd, expose the size using the
size = lseek(fd, SEEK_END, 0); lseek(fd, SEEK_CUR, 0);
idiom.

v2: Added Daniel's sugeested documentation, with minor fixups

Signed-off-by: Christopher James Halse Rogers 
Reviewed-by: Daniel Vetter 
Tested-by: Daniel Vetter 
Signed-off-by: Sumit Semwal

doc: Fix typo in doucmentations

2013-07-25T10:34:15+00:00

Correct typo (double words) in documentations.

Signed-off-by: Masanari Iida 
Acked-by: Randy Dunlap 
Signed-off-by: Jiri Kosina

dma-buf: replace dma_buf_export() with dma_buf_export_named()

2013-05-01T11:05:36+00:00

For debugging purposes, it is useful to have a name-string added
while exporting buffers. Hence, dma_buf_export() is replaced with
dma_buf_export_named(), which additionally takes 'exp_name' as a
parameter.

For backward compatibility, and for lazy exporters who don't wish to
name themselves, a #define dma_buf_export() is also made available,
which adds a __FILE__ instead of 'exp_name'.

Cc: Daniel Vetter 
  [Thanks for the idea!]
Reviewed-by: Daniel Vetter 
Signed-off-by: Sumit Semwal