28 Mar
2016
28 Mar
'16
11:14 p.m.
On 03/28/2016 12:28 PM, Mauro Carvalho Chehab wrote:
Em Fri, 25 Mar 2016 22:38:43 -0600 Shuah Khan shuahkh@osg.samsung.com escreveu:
Add Media Device Allocator API documentation.
Please merge this with the previous patch.
Yes. I will merge them.
-- Shuah
Signed-off-by: Shuah Khan shuahkh@osg.samsung.com
include/media/media-dev-allocator.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
diff --git a/include/media/media-dev-allocator.h b/include/media/media-dev-allocator.h index 2932c90..174840c 100644 --- a/include/media/media-dev-allocator.h +++ b/include/media/media-dev-allocator.h @@ -20,6 +20,38 @@
#ifdef CONFIG_MEDIA_CONTROLLER /**
- DOC: Media Controller Device Allocator API
- There are known problems with media device life time management. When media
- device is released while an media ioctl is in progress, ioctls fail with
- use-after-free errors and kernel hangs in some cases.
- Media Device can be in any the following states:
- Allocated
- Registered (could be tied to more than one driver)
- Unregistered, not in use (media device file is not open)
- Unregistered, in use (media device file is not open)
- Released
- When media device belongs to more than one driver, registrations should be
- refcounted to avoid unregistering when one of the drivers does unregister.
- A refcount field in the struct media_device covers this case. Unregister on
- a Media Allocator media device is a kref_put() call. The media device should
- be unregistered only when the last unregister occurs.
- When a media device is in use when it is unregistered, it should not be
- released until the application exits when it detects the unregistered
- status. Media device that is in use when it is unregistered is moved to
- to_delete_list. When the last unregister occurs, media device is unregistered
- and becomes an unregistered, still allocated device. Unregister marks the
- device to be deleted.
- When media device belongs to more than one driver, as both drivers could be
- unbound/bound, driver should not end up getting stale media device that is
- on its way out. Moving the unregistered media device to to_delete_list helps
- this case as well.
- */
+/**
- media_device_get() - Allocate and return global media device
- @mdev