From 21636363be97725432591071d26dc0dca088ecbb Mon Sep 17 00:00:00 2001 From: Pawel Osciak Date: Wed, 28 Apr 2010 04:05:23 -0300 Subject: V4L/DVB: Add documentation for the new error flag Add documentation for V4L2_BUF_FLAG_ERROR. Signed-off-by: Pawel Osciak Signed-off-by: Kyungmin Park Signed-off-by: Mauro Carvalho Chehab diff --git a/Documentation/DocBook/v4l/io.xml b/Documentation/DocBook/v4l/io.xml index bb685ed..d424886 100644 --- a/Documentation/DocBook/v4l/io.xml +++ b/Documentation/DocBook/v4l/io.xml @@ -702,6 +702,16 @@ They can be both cleared however, then the buffer is in "dequeued" state, in the application domain to say so. + V4L2_BUF_FLAG_ERROR + 0x0040 + When this flag is set, the buffer has been dequeued + successfully, although the data might have been corrupted. + This is recoverable, streaming may continue as normal and + the buffer may be reused normally. + Drivers set this flag when the VIDIOC_DQBUF + ioctl is called. + + V4L2_BUF_FLAG_KEYFRAME 0x0008 Drivers set or clear this flag when calling the diff --git a/Documentation/DocBook/v4l/vidioc-qbuf.xml b/Documentation/DocBook/v4l/vidioc-qbuf.xml index b843bd7..ab691eb 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 reserved fields of a &v4l2-buffer; as above, when VIDIOC_DQBUF is called with a pointer to this structure the driver fills the -remaining fields or returns an error code. +remaining fields or returns an error code. The driver may also set +V4L2_BUF_FLAG_ERROR in the flags +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. By default VIDIOC_DQBUF blocks when no buffer is in the outgoing queue. When the @@ -158,7 +162,13 @@ enqueue a user pointer buffer. VIDIOC_DQBUF 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. +returning an error, or even stop capturing. Reusing such buffer may be unsafe +though and its details (e.g. index) may not be +returned either. It is recommended that drivers indicate recoverable errors +by setting the V4L2_BUF_FLAG_ERROR and returning 0 instead. +In that case the application should be able to safely reuse the buffer and +continue streaming. + -- cgit v0.10.2