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authorEzequiel Garcia <ezequiel@collabora.com>2019-12-05 15:24:40 +0100
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>2019-12-16 10:24:55 +0100
commit0fb36893c6c129d48965332a23fa4ea6b075ad0c (patch)
treeb3f05b02e985c7a4274d2a2e4f7c3f7f26924655 /Documentation/media
parent961f97ab1ef3e2dbe43fac4913372f58ca4a5f74 (diff)
media: vidioc-enum-fmt.rst: clarify format preference
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@collabora.com> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'Documentation/media')
-rw-r--r--Documentation/media/uapi/v4l/vidioc-enum-fmt.rst4
1 files changed, 3 insertions, 1 deletions
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::