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Diffstat (limited to 'Documentation/usb')
| -rw-r--r-- | Documentation/usb/gadget_uvc.rst | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/Documentation/usb/gadget_uvc.rst b/Documentation/usb/gadget_uvc.rst index 6d22faceb1a0..62bd81ba3dd1 100644 --- a/Documentation/usb/gadget_uvc.rst +++ b/Documentation/usb/gadget_uvc.rst @@ -275,6 +275,34 @@ out with 0x00, for example: bNrInPins and baSourceID function in the same way. +Configuring Supported Controls for Camera Terminal and Processing Unit +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The Camera Terminal and Processing Units in the UVC chain also have bmControls +attributes which function similarly to the same field in an Extension Unit. +Unlike XUs however, the meaning of the bitflag for these units is defined in +the UVC specification; you should consult the "Camera Terminal Descriptor" and +"Processing Unit Descriptor" sections for an enumeration of the flags. + +.. code-block:: bash + + # Set the Processing Unit's bmControls, flagging Brightness, Contrast + # and Hue as available controls: + echo 0x05 > $FUNCTION/control/processing/default/bmControls + + # Set the Camera Terminal's bmControls, flagging Focus Absolute and + # Focus Relative as available controls: + echo 0x60 > $FUNCTION/control/terminal/camera/default/bmControls + +If you do not set these fields then by default the Auto-Exposure Mode control +for the Camera Terminal and the Brightness control for the Processing Unit will +be flagged as available; if they are not supported you should set the field to +0x00. + +Note that the size of the bmControls field for a Camera Terminal or Processing +Unit is fixed by the UVC specification, and so the bControlSize attribute is +read-only here. + Custom Strings Support ~~~~~~~~~~~~~~~~~~~~~~ |