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>`.
.. _V4L2-BUF-CAP-SUPPORTS-USERPTR:
.. _V4L2-BUF-CAP-SUPPORTS-DMABUF:
.. _V4L2-BUF-CAP-SUPPORTS-REQUESTS:
+.. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
.. cssclass:: longtable
* - ``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
============
* are not in use and can be freed.
*/
mutex_lock(&q->mmap_lock);
- if (q->memory == VB2_MEMORY_MMAP && __buffers_in_use(q)) {
- mutex_unlock(&q->mmap_lock);
- dprintk(1, "memory in use, cannot free\n");
- return -EBUSY;
- }
+ if (debug && q->memory == VB2_MEMORY_MMAP &&
+ __buffers_in_use(q))
+ dprintk(1, "memory in use, orphaning buffers\n");
/*
* Call queue_cancel to clean up any buffers in the
#define V4L2_BUF_CAP_SUPPORTS_USERPTR (1 << 1)
#define V4L2_BUF_CAP_SUPPORTS_DMABUF (1 << 2)
#define V4L2_BUF_CAP_SUPPORTS_REQUESTS (1 << 3)
+#define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4)
/**
* struct v4l2_plane - plane info for multi-planar buffers