diff options
Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-qbuf.xml')
| -rw-r--r-- | Documentation/DocBook/v4l/vidioc-qbuf.xml | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/Documentation/DocBook/v4l/vidioc-qbuf.xml b/Documentation/DocBook/v4l/vidioc-qbuf.xml index b843bd7b389..ab691ebf3b9 100644 --- a/Documentation/DocBook/v4l/vidioc-qbuf.xml +++ b/Documentation/DocBook/v4l/vidioc-qbuf.xml @@ -111,7 +111,11 @@ from the driver's outgoing queue. They just set the and <structfield>reserved</structfield> fields of a &v4l2-buffer; as above, when <constant>VIDIOC_DQBUF</constant> is called with a pointer to this structure the driver fills the -remaining fields or returns an error code.</para> +remaining fields or returns an error code. The driver may also set +<constant>V4L2_BUF_FLAG_ERROR</constant> in the <structfield>flags</structfield> +field. It indicates a non-critical (recoverable) streaming error. In such case +the application may continue as normal, but should be aware that data in the +dequeued buffer might be corrupted.</para> <para>By default <constant>VIDIOC_DQBUF</constant> blocks when no buffer is in the outgoing queue. When the @@ -158,7 +162,13 @@ enqueue a user pointer buffer.</para> <para><constant>VIDIOC_DQBUF</constant> failed due to an internal error. Can also indicate temporary problems like signal loss. Note the driver might dequeue an (empty) buffer despite -returning an error, or even stop capturing.</para> +returning an error, or even stop capturing. Reusing such buffer may be unsafe +though and its details (e.g. <structfield>index</structfield>) may not be +returned either. It is recommended that drivers indicate recoverable errors +by setting the <constant>V4L2_BUF_FLAG_ERROR</constant> and returning 0 instead. +In that case the application should be able to safely reuse the buffer and +continue streaming. + </para> </listitem> </varlistentry> </variablelist> |