Commit 78866efe authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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[media] v4l2-controls.txt: update to latest v4l2-ctrl.c changes 



Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent ddac5c10

Documentation/video4linux/v4l2-controls.txt

+4 −9
Original line number Diff line number Diff line
@@ -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.





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