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authorBenjamin Gaignard <benjamin.gaignard@collabora.com>2024-03-14 18:32:24 +0300
committerHans Verkuil <hverkuil-cisco@xs4all.nl>2024-03-25 14:00:44 +0300
commita3293a85381ec9680aa2929547fbc76c5d87a1b2 (patch)
tree775ded5621e70cec625921830c48dc3d2c97faae /Documentation/userspace-api
parent5fb19f20926127d082d7dbc2b5c4d7b0b215ce03 (diff)
downloadlinux-a3293a85381ec9680aa2929547fbc76c5d87a1b2.tar.xz
media: v4l2: Add REMOVE_BUFS ioctl
VIDIOC_REMOVE_BUFS ioctl allows to remove buffers from a queue. The number of buffers to remove in given by count field of struct v4l2_remove_buffers and the range start at the index specified in the same structure. Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> [hverkuil: vidioc-remove-bufs.rst: mention no bufs are freed on error]
Diffstat (limited to 'Documentation/userspace-api')
-rw-r--r--Documentation/userspace-api/media/v4l/user-func.rst1
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst86
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst1
3 files changed, 88 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
index 15ff0bf7bbe6..6f661138801c 100644
--- a/Documentation/userspace-api/media/v4l/user-func.rst
+++ b/Documentation/userspace-api/media/v4l/user-func.rst
@@ -62,6 +62,7 @@ Function Reference
vidioc-query-dv-timings
vidioc-querystd
vidioc-reqbufs
+ vidioc-remove-bufs
vidioc-s-hw-freq-seek
vidioc-streamon
vidioc-subdev-enum-frame-interval
diff --git a/Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst
new file mode 100644
index 000000000000..1995b39af9ba
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst
@@ -0,0 +1,86 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_REMOVE_BUFS:
+
+************************
+ioctl VIDIOC_REMOVE_BUFS
+************************
+
+Name
+====
+
+VIDIOC_REMOVE_BUFS - Removes buffers from a queue
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_REMOVE_BUFS
+
+``int ioctl(int fd, VIDIOC_REMOVE_BUFS, struct v4l2_remove_buffers *argp)``
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :c:func:`open()`.
+
+``argp``
+ Pointer to struct :c:type:`v4l2_remove_buffers`.
+
+Description
+===========
+
+Applications can optionally call the :ref:`VIDIOC_REMOVE_BUFS` ioctl to
+remove buffers from a queue.
+:ref:`VIDIOC_CREATE_BUFS` ioctl support is mandatory to enable :ref:`VIDIOC_REMOVE_BUFS`.
+This ioctl is available if the ``V4L2_BUF_CAP_SUPPORTS_REMOVE_BUFS`` capability
+is set on the queue when :c:func:`VIDIOC_REQBUFS` or :c:func:`VIDIOC_CREATE_BUFS`
+are invoked.
+
+.. c:type:: v4l2_remove_buffers
+
+.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
+
+.. flat-table:: struct v4l2_remove_buffers
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+ * - __u32
+ - ``index``
+ - The starting buffer index to remove. This field is ignored if count == 0.
+ * - __u32
+ - ``count``
+ - The number of buffers to be removed with indices 'index' until 'index + count - 1'.
+ All buffers in this range must be valid and in DEQUEUED state.
+ :ref:`VIDIOC_REMOVE_BUFS` will always check the validity of ``type`, if it is
+ invalid it returns ``EINVAL`` error code.
+ If count is set to 0 :ref:`VIDIOC_REMOVE_BUFS` will do nothing and return 0.
+ * - __u32
+ - ``type``
+ - Type of the stream or buffers, this is the same as the struct
+ :c:type:`v4l2_format` ``type`` field. See
+ :c:type:`v4l2_buf_type` for valid values.
+ * - __u32
+ - ``reserved``\ [13]
+ - A place holder for future extensions. Drivers and applications
+ must set the array to zero.
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter. If an error occurs, no
+buffers will be freed and one of the error codes below will be returned:
+
+EBUSY
+ File I/O is in progress.
+ One or more of the buffers in the range ``index`` to ``index + count - 1`` are not
+ in DEQUEUED state.
+
+EINVAL
+ One or more of the buffers in the range ``index`` to ``index + count - 1`` do not
+ exist in the queue.
+ The buffer type (``type`` field) is not valid.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
index 0b3a41a45d05..bbc22dd76032 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
@@ -121,6 +121,7 @@ aborting or finishing any DMA in progress, an implicit
.. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
.. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
.. _V4L2-BUF-CAP-SUPPORTS-MAX-NUM-BUFFERS:
+.. _V4L2-BUF-CAP-SUPPORTS-REMOVE-BUFS:
.. raw:: latex