From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
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 bc24be4..65d4652 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:
@@ -638,9 +635,7 @@ 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
--
1.7.1
--
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