From: Ezequiel Garcia <ezequiel@collabora.com>
To: linux-media@vger.kernel.org
Cc: kernel@collabora.com, Tomasz Figa <tfiga@chromium.org>,
linux-rockchip@lists.infradead.org,
Heiko Stuebner <heiko@sntech.de>, Jonas Karlman <jonas@kwiboo.se>,
Philipp Zabel <p.zabel@pengutronix.de>,
Boris Brezillon <boris.brezillon@collabora.com>,
Chris Healy <cphealy@gmail.com>,
linux-kernel@vger.kernel.org,
Ezequiel Garcia <ezequiel@collabora.com>
Subject: [PATCH v4 1/4] media: vidioc-enum-fmt.rst: clarify format preference
Date: Thu, 5 Dec 2019 11:24:40 -0300 [thread overview]
Message-ID: <20191205142443.1298-2-ezequiel@collabora.com> (raw)
In-Reply-To: <20191205142443.1298-1-ezequiel@collabora.com>
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>
---
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::
--
2.22.0
next prev parent reply other threads:[~2019-12-05 14:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 14:24 [PATCH v4 0/4] Enable Hantro G1 post-processor Ezequiel Garcia
2019-12-05 14:24 ` Ezequiel Garcia [this message]
2019-12-05 14:24 ` [PATCH v4 2/4] media: hantro: Cleanup format negotiation helpers Ezequiel Garcia
2019-12-05 14:24 ` Ezequiel Garcia
2019-12-05 14:24 ` [PATCH v4 3/4] hantro: Rename {prepare,finish}_run to {start,end}_prepare_run Ezequiel Garcia
2019-12-05 14:24 ` [PATCH v4 3/4] hantro: Rename {prepare, finish}_run to {start, end}_prepare_run Ezequiel Garcia
2019-12-05 14:24 ` [PATCH v4 4/4] media: hantro: Support color conversion via post-processing Ezequiel Garcia
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