On 2/22/19 6:28 PM, Shuah Khan wrote: > Media Device Allocator API to allows multiple drivers share a media device. > This API solves a very common use-case for media devices where one physical > device (an USB stick) provides both audio and video. When such media device > exposes a standard USB Audio class, a proprietary Video class, two or more > independent drivers will share a single physical USB bridge. In such cases, > it is necessary to coordinate access to the shared resource. > > 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. While doing the final compile tests for the pull request I encountered the following sparse warnings: sparse: WARNINGS /home/hans/work/build/media-git/drivers/media/usb/au0828/au0828-core.c:282:6: warning: this statement may fall through [-Wimplicit-fallthrough=] SPARSE:/home/hans/work/build/media-git/drivers/media/media-dev-allocator.c /home/hans/work/build/media-git/drivers/media/media-dev-allocator.c:94:21: warning: symbol 'media_device_usb_allocate' was not declared. Should it be static? SPARSE:/home/hans/work/build/media-git/drivers/media/media-dev-allocator.c /home/hans/work/build/media-git/drivers/media/media-dev-allocator.c:120:6: warning: symbol 'media_device_delete' was not declared. Should it be static? /home/hans/work/build/media-git/drivers/media/media-dev-allocator.c:94:22: warning: no previous prototype for 'media_device_usb_allocate' [-Wmissing-prototypes] /home/hans/work/build/media-git/drivers/media/media-dev-allocator.c:120:6: warning: no previous prototype for 'media_device_delete' [-Wmissing-prototypes] Can you fix these issues and post a v12? Thanks! Hans > > - This patch series in rested on 5.0-rc7 and addresses comments on > v10 series from Hans Verkuil. Fixed problems found in resource > sharing logic in au0828 adding a patch 5 to this series. > - I am sharing the test plan used for testing resource sharing which > could serve as a regression test plan. Test results can be found at: > > https://docs.google.com/document/d/1XMs3HYgLiHby6xVIvIxv75KSXAAN3F4uUpw2uLuD9c4/edit?usp=sharing > > - v10 was tested on 5.0-rc3 and addresses comments on v9 series from > Hans Verkuil. > - v9 was tested on 4.20-rc6. > - Tested sharing resources with kaffeine, vlc, xawtv, tvtime, and > arecord. When analog is streaming, digital and audio user-space > applications detect that the tuner is busy and exit. When digital > is streaming, analog and audio applications detect that the tuner is > busy and exit. When arecord is owns the tuner, digital and analog > detect that the tuner is busy and exit. > - Tested media device allocator API with bind/unbind testing on > snd-usb-audio and au0828 drivers to make sure /dev/mediaX is released > only when the last driver is unbound. > - Addressed review comments from Hans on the RFC v8 (rebased on 4.19) > - Updated change log to describe the use-case more clearly. > - No changes to 0001,0002 code since the v7 referenced below. > - 0003 is a new patch to enable ALSA defines that have been > disabled for kernel between 4.9 and 4.19. > - Minor merge conflict resolution in 0004. > - Added SPDX to new files. > > Changes since v10: > - Patch 1: Fixed SPDX tag and removed redundant IS_ENABLED(CONFIG_USB) > around media_device_usb_allocate() - Sakari Ailus's review > comment. > - Patch 2 and 3: No changes > - Patch 4: Fixed SPDX tag - Sakari Ailus's review comment. > - Carried Reviewed-by tag from Takashi Iwai for the sound from v9. > - Patch 5: This is a new patch added to fix resource sharing > inconsistencies and problem found during testing using Han's > tests. > Changes since v9: > - Patch 1: Fix mutex assert warning from find_module() calls. This > code was written before the change to find_module() that requires > callers to hold module_mutex. I missed this during my testing on > 4.20-rc6. Hans Verkuil reported the problem. > - Patch 4: sound/usb: Initializes all the entities it can before > registering the device based on comments from Hans Verkuil > - Carried Reviewed-by tag from Takashi Iwai for the sound from v9. > - No changes to Patches 2 and 3. > > References: > https://lkml.org/lkml/2018/11/2/169 > https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg105854.html > > Shuah Khan (5): > media: Media Device Allocator API > media: change au0828 to use Media Device Allocator API > media: media.h: Enable ALSA MEDIA_INTF_T* interface types > sound/usb: Use Media Controller API to share media resources > au0828: fix enable and disable source audio and video inconsistencies > > Documentation/media/kapi/mc-core.rst | 41 ++++ > drivers/media/Makefile | 4 + > drivers/media/media-dev-allocator.c | 142 +++++++++++ > drivers/media/usb/au0828/au0828-core.c | 190 ++++++++++---- > drivers/media/usb/au0828/au0828.h | 6 +- > include/media/media-dev-allocator.h | 53 ++++ > include/uapi/linux/media.h | 25 +- > sound/usb/Kconfig | 4 + > sound/usb/Makefile | 2 + > sound/usb/card.c | 14 ++ > sound/usb/card.h | 3 + > sound/usb/media.c | 327 +++++++++++++++++++++++++ > sound/usb/media.h | 74 ++++++ > sound/usb/mixer.h | 3 + > sound/usb/pcm.c | 29 ++- > sound/usb/quirks-table.h | 1 + > sound/usb/stream.c | 2 + > sound/usb/usbaudio.h | 6 + > 18 files changed, 865 insertions(+), 61 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 >
