[alsa-devel] [PATCH v6 0/3] Media Device Allocator API

[Shuah Khan]

Media Device Allocator API to allows multiple drivers share a media device.
Using this API, drivers can allocate a media device with the shared struct
device as the key. Once the media device is allocated by a driver, other
drivers can get a reference to it. The media device is released when all
the references are released.

Patches 0001 and 0002 are rebased to 4.9-rc7. Patch 0003 for snd-usb-audio
is a rebase of the patch that was tested with the original Media Device
Allocator patch series.

snd-usb-audio patch includes the fixes found during 4.7-rc1 time in the
original snd-usb-audio patch.

Changes to patches in this series:
Changes to patch 0001 since v5: (comments from Mauro and Sakari)
- Removed struct device from media_device_instance. mdev.dev is used instead.
- Added documentation.

Changes to patch 0002:
- No changes since patch v2, applies cleanly on top of the following:
media: Protect enable_source and disable_source handler code paths
https://lkml.org/lkml/2016/11/29/1001
 
Changes to patch 0003:
- Changed to hold graph_mutex to check and call enable_source and
  disable_source handlers - to match au0828 doing the same in:
media: Protect enable_source and disable_source handler code paths 
https://lkml.org/lkml/2016/11/29/1001

Changes to patch 0001 since v4:
- Addressed Sakari's review comments with the exception of
  opting to not introduce media_device_usb_allocate() macro,
  and to not add a new routine to find media device instance
  to avoid a one line check.

Changes to patch 0001 since v3:
- Fixed undefined reference to `__media_device_usb_init compile error when
  CONFIG_USB is disabled.
- Fixed kernel paging error when accessing /dev/mediaX after rmmod of the
  module that owns the media_device. The fix bumps the reference count for
  the owner when second driver comes along to share the media_device. If
  au0828 owns the media_device, then snd_usb_audio will bump the refcount
  for au0828, so it won't get deleted and vice versa.

Changes to patch 0002 since v2:
- Updated media_device_delete() to pass in module name.

Changes to patch 0003 since the last version in 4.7-rc1:
- Included fixes to bugs found during testing. 
- Updated to use the Media Allocator API.

This patch series has been tested with au0828 and snd-usb-audio drivers.
Ran bind and unbind loop tests on each driver with mc_nextgen_test and
media_device_test app loop tests while checking lsmod and dmesg.

Please refer to tools/testing/selftests/media_tests/regression_test.txt
for testing done on this series.

Shuah Khan (3):
  media: Media Device Allocator API
  media: change au0828 to use Media Device Allocator API
  sound/usb: Use Media Controller API to share media resources

 Documentation/media/kapi/mc-core.rst   |  37 ++++
 drivers/media/Makefile                 |   3 +-
 drivers/media/media-dev-allocator.c    | 133 ++++++++++++++
 drivers/media/usb/au0828/au0828-core.c |  12 +-
 drivers/media/usb/au0828/au0828.h      |   1 +
 include/media/media-dev-allocator.h    |  54 ++++++
 sound/usb/Kconfig                      |   4 +
 sound/usb/Makefile                     |   2 +
 sound/usb/card.c                       |  14 ++
 sound/usb/card.h                       |   3 +
 sound/usb/media.c                      | 326 +++++++++++++++++++++++++++++++++
 sound/usb/media.h                      |  73 ++++++++
 sound/usb/mixer.h                      |   3 +
 sound/usb/pcm.c                        |  28 ++-
 sound/usb/quirks-table.h               |   1 +
 sound/usb/stream.c                     |   2 +
 sound/usb/usbaudio.h                   |   6 +
 17 files changed, 688 insertions(+), 14 deletions(-)
 create mode 100644 drivers/media/media-dev-allocator.c
 create mode 100644 include/media/media-dev-allocator.h
 create mode 100644 sound/usb/media.c
 create mode 100644 sound/usb/media.h

-- 
2.7.4