On Wed, 13 Nov 2019 14:56:03 -0300 Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> wrote: > It has been decided to use the ENUM_FMT index value > as a hint for driver preference. This is defined purposedly > in a very liberal way, letting drivers define what "preference" > means. > > For instance, the Hantro VPU driver indicates additional > processing to output a given format, and thus implicates > more CPU usage, which is enumerated after native (non-processed) > formats. > > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> > --- > Documentation/media/uapi/v4l/vidioc-enum-fmt.rst | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > index 399ef1062bac..8ca6ab701e4a 100644 > --- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > +++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst > @@ -44,7 +44,9 @@ To enumerate image formats applications initialize the ``type`` and > the :ref:`VIDIOC_ENUM_FMT` ioctl with a pointer to this structure. Drivers > fill the rest of the structure or return an ``EINVAL`` error code. All > formats are enumerable by beginning at index zero and incrementing by > -one until ``EINVAL`` is returned. > +one until ``EINVAL`` is returned. If applicable, drivers shall return > +formats in preference order, where preferred formats are returned before > +(that is, with lower ``index`` value) less-preferred formats. > > .. note:: >
