tree 0a308c80affcc39c2c869f29f1109e5ee9d6140f
parent a8db3c1948eb30cd6988b5b96b654f591e6280b1
author Richard Purdie <rpurdie@rpsys.net> 1170973509 +0000
committer Richard Purdie <rpurdie@rpsys.net> 1171960725 +0000

backlight: Fix external uses of backlight internal semaphore

backlight_device->sem has a very specific use as documented in the
header file. The external users of this are using it for a different
reason, to serialise access to the update_status() method.

backlight users were supposed to implement their own internal
serialisation of update_status() if needed but everyone is doing
things differently and incorrectly. Therefore add a global mutex to
take care of serialisation for everyone, once and for all.

Locking for get_brightness remains optional since most users don't
need it.

Also update the lcd class in a similar way.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>