From 503c3d829eaf48837dd5bff5d97ad66369bb955a Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Sun, 7 Mar 2010 15:04:59 -0300 Subject: [media] media: Entity use count Due to the wide differences between drivers regarding power management needs, the media controller does not implement power management. However, the media_entity structure includes a use_count field that media drivers can use to track the number of users of every entity for power management needs. The use_count field is owned by media drivers and must not be touched by entity drivers. Access to the field must be protected by the media device graph_mutex lock. Signed-off-by: Laurent Pinchart Acked-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/media-framework.txt | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'Documentation/media-framework.txt') diff --git a/Documentation/media-framework.txt b/Documentation/media-framework.txt index ab17f33ddedc..78ae02095372 100644 --- a/Documentation/media-framework.txt +++ b/Documentation/media-framework.txt @@ -258,3 +258,16 @@ When the graph traversal is complete the function will return NULL. Graph traversal can be interrupted at any moment. No cleanup function call is required and the graph structure can be freed normally. + + +Use count and power handling +---------------------------- + +Due to the wide differences between drivers regarding power management needs, +the media controller does not implement power management. However, the +media_entity structure includes a use_count field that media drivers can use to +track the number of users of every entity for power management needs. + +The use_count field is owned by media drivers and must not be touched by entity +drivers. Access to the field must be protected by the media device graph_mutex +lock. -- cgit v1.2.3-59-g8ed1b