diff options
Diffstat (limited to 'Documentation/video4linux/v4l2-controls.txt')
| -rw-r--r-- | Documentation/video4linux/v4l2-controls.txt | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt index 881e7f44491b..95a381309d08 100644 --- a/Documentation/video4linux/v4l2-controls.txt +++ b/Documentation/video4linux/v4l2-controls.txt @@ -277,16 +277,13 @@ implement g_volatile_ctrl like this: { switch (ctrl->id) { case V4L2_CID_BRIGHTNESS: - ctrl->cur.val = read_reg(0x123); + ctrl->val = read_reg(0x123); break; } } -The 'new value' union is not used in g_volatile_ctrl. In general controls -that need to implement g_volatile_ctrl are read-only controls. - -Note that if one or more controls in a control cluster are marked as volatile, -then all the controls in the cluster are seen as volatile. +Note that you use the 'new value' union as well in g_volatile_ctrl. In general +controls that need to implement g_volatile_ctrl are read-only controls. To mark a control as volatile you have to set the is_volatile flag: @@ -636,9 +633,7 @@ button controls are write-only controls. -EINVAL as the spec says. 5) The spec does not mention what should happen when you try to set/get a -control class controls. ivtv currently returns -EINVAL (indicating that the -control ID does not exist) while the framework will return -EACCES, which -makes more sense. +control class controls. The framework will return -EACCES. Proposals for Extensions |