LinuxTV Patchwork [PATCHv4,04/10] buffer.rst: document the new buffer tag feature.

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Submitter Hans Verkuil
Date Dec. 5, 2018, 10:20 a.m.
Message ID <20181205102040.11741-5-hverkuil-cisco@xs4all.nl>
Download mbox | patch
Permalink /patch/53311/
State Superseded
Delegated to: Hans Verkuil
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Comments

Hans Verkuil - Dec. 5, 2018, 10:20 a.m.
From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Document V4L2_BUF_FLAG_TAG.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
---
 Documentation/media/uapi/v4l/buffer.rst         | 17 ++++++++++++++---
 Documentation/media/uapi/v4l/vidioc-reqbufs.rst |  4 ++++
 2 files changed, 18 insertions(+), 3 deletions(-)

Patch

diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst
index 2e266d32470a..f83ee00cb30b 100644
--- a/Documentation/media/uapi/v4l/buffer.rst
+++ b/Documentation/media/uapi/v4l/buffer.rst
@@ -301,10 +301,13 @@  struct v4l2_buffer
 	elements in the ``planes`` array. The driver will fill in the
 	actual number of valid elements in that array.
     * - __u32
-      - ``reserved2``
+      - ``tag``
       -
-      - A place holder for future extensions. Drivers and applications
-	must set this to 0.
+      - When the ``V4L2_BUF_FLAG_TAG`` flag is set in ``flags``, this
+	field contains a user-specified tag value.
+
+	It is used by stateless codecs where this tag can be used to
+	refer to buffers that contain reference frames.
     * - __u32
       - ``request_fd``
       -
@@ -567,6 +570,14 @@  Buffer Flags
 	when the ``VIDIOC_DQBUF`` ioctl is called. Applications can set
 	this bit and the corresponding ``timecode`` structure when
 	``type`` refers to an output stream.
+    * .. _`V4L2-BUF-FLAG-TAG`:
+
+      - ``V4L2_BUF_FLAG_TAG``
+      - 0x00000200
+      - The ``tag`` field is valid. Applications can set
+	this bit and the corresponding ``tag`` field. If tags are
+	supported then the ``V4L2_BUF_CAP_SUPPORTS_TAGS`` capability
+	is also set.
     * .. _`V4L2-BUF-FLAG-PREPARED`:
 
       - ``V4L2_BUF_FLAG_PREPARED``
diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
index e62a15782790..38a7d0aee483 100644
--- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
@@ -118,6 +118,7 @@  aborting or finishing any DMA in progress, an implicit
 .. _V4L2-BUF-CAP-SUPPORTS-DMABUF:
 .. _V4L2-BUF-CAP-SUPPORTS-REQUESTS:
 .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
+.. _V4L2-BUF-CAP-SUPPORTS-TAGS:
 
 .. cssclass:: longtable
 
@@ -143,6 +144,9 @@  aborting or finishing any DMA in progress, an implicit
       - The kernel allows calling :ref:`VIDIOC_REQBUFS` while buffers are still
         mapped or exported via DMABUF. These orphaned buffers will be freed
         when they are unmapped or when the exported DMABUF fds are closed.
+    * - ``V4L2_BUF_CAP_SUPPORTS_TAGS``
+      - 0x00000020
+      - This buffer type supports ``V4L2_BUF_FLAG_TAG``.
 
 Return Value
 ============

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