diff options
Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst | 39 |
1 files changed, 27 insertions, 12 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst index 248f6f9ee7c5..4ad7dec27e25 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst @@ -31,15 +31,28 @@ Arguments Description =========== -To enumerate media bus formats available at a given sub-device pad -applications initialize the ``pad``, ``which`` and ``index`` fields of -struct -:c:type:`v4l2_subdev_mbus_code_enum` and -call the :ref:`VIDIOC_SUBDEV_ENUM_MBUS_CODE` ioctl with a pointer to this -structure. Drivers fill the rest of the structure or return an ``EINVAL`` -error code if either the ``pad`` or ``index`` are invalid. All media bus -formats are enumerable by beginning at index zero and incrementing by -one until ``EINVAL`` is returned. +This call is used by the application to access the enumeration +of media bus formats for the selected pad. + +The enumerations are defined by the driver, and indexed using the ``index`` field +of struct :c:type:`v4l2_subdev_mbus_code_enum`. +Each enumeration starts with the ``index`` of 0, and +the lowest invalid index marks the end of enumeration. + +Therefore, to enumerate media bus formats available at a given sub-device pad, +initialize the ``pad``, and ``which`` fields to desired values, +and set ``index`` to 0. +Then call the :ref:`VIDIOC_SUBDEV_ENUM_MBUS_CODE` ioctl +with a pointer to this structure. + +A successful call will return with the ``code`` field filled in +with a mbus code value. +Repeat with increasing ``index`` until ``EINVAL`` is received. +``EINVAL`` means that either ``pad`` is invalid, +or that there are no more codes available at this pad. + +The driver must not return the same value of ``code`` for different indices +at the same pad. Available media bus formats may depend on the current 'try' formats at other pads of the sub-device, as well as on the current active links. @@ -57,14 +70,16 @@ information about the try formats. * - __u32 - ``pad`` - - Pad number as reported by the media controller API. + - Pad number as reported by the media controller API. Filled in by the + application. * - __u32 - ``index`` - - Number of the format in the enumeration, set by the application. + - Index of the mbus code in the enumeration belonging to the given pad. + Filled in by the application. * - __u32 - ``code`` - The media bus format code, as defined in - :ref:`v4l2-mbus-format`. + :ref:`v4l2-mbus-format`. Filled in by the driver. * - __u32 - ``which`` - Media bus format codes to be enumerated, from enum |