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-rw-r--r--Documentation/media/uapi/v4l/vidioc-reqbufs.rst26
1 files changed, 22 insertions, 4 deletions
diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
index d4bbbb0c60e8..d7faef10e39b 100644
--- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
@@ -1,4 +1,11 @@
-.. -*- coding: utf-8; mode: rst -*-
+.. Permission is granted to copy, distribute and/or modify this
+.. document under the terms of the GNU Free Documentation License,
+.. Version 1.1 or any later version published by the Free Software
+.. Foundation, with no Invariant Sections, no Front-Cover Texts
+.. and no Back-Cover Texts. A copy of the license is included at
+.. Documentation/media/uapi/fdl-appendix.rst.
+..
+.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
.. _VIDIOC_REQBUFS:
@@ -59,9 +66,14 @@ When the I/O method is not supported the ioctl returns an ``EINVAL`` error
code.
Applications can call :ref:`VIDIOC_REQBUFS` again to change the number of
-buffers, however this cannot succeed when any buffers are still mapped.
-A ``count`` value of zero frees all buffers, after aborting or finishing
-any DMA in progress, an implicit
+buffers. Note that if any buffers are still mapped or exported via DMABUF,
+then :ref:`VIDIOC_REQBUFS` can only succeed if the
+``V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS`` capability is set. Otherwise
+:ref:`VIDIOC_REQBUFS` will return the ``EBUSY`` error code.
+If ``V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS`` is set, then these buffers are
+orphaned and will be freed when they are unmapped or when the exported DMABUF
+fds are closed. A ``count`` value of zero frees or orphans all buffers, after
+aborting or finishing any DMA in progress, an implicit
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>`.
@@ -112,6 +124,7 @@ any DMA in progress, an implicit
.. _V4L2-BUF-CAP-SUPPORTS-USERPTR:
.. _V4L2-BUF-CAP-SUPPORTS-DMABUF:
.. _V4L2-BUF-CAP-SUPPORTS-REQUESTS:
+.. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
.. cssclass:: longtable
@@ -132,6 +145,11 @@ any DMA in progress, an implicit
* - ``V4L2_BUF_CAP_SUPPORTS_REQUESTS``
- 0x00000008
- This buffer type supports :ref:`requests <media-request-api>`.
+ * - ``V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS``
+ - 0x00000010
+ - 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.
Return Value
============