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V4L/DVB: Add documentation for the new error flag 

Add documentation for V4L2_BUF_FLAG_ERROR.

Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
hifive-unleashed-5.1
Pawel Osciak 2010-04-28 04:05:23 -03:00 committed by Mauro Carvalho Chehab
parent b2dfd1a45f
commit 21636363be
2 changed files with 22 additions and 2 deletions
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10
Documentation/DocBook/v4l/io.xml
View File

@ -701,6 +701,16 @@ buffer cannot be on both queues at the same time, the
They can be both cleared however, then the buffer is in "dequeued"
state, in the application domain to say so.</entry>
</row>
<row>
<entry><constant>V4L2_BUF_FLAG_ERROR</constant></entry>
<entry>0x0040</entry>
<entry>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 <constant>VIDIOC_DQBUF</constant>
ioctl is called.</entry>
</row>
<row>
<entry><constant>V4L2_BUF_FLAG_KEYFRAME</constant></entry>
<entry>0x0008</entry>

14
Documentation/DocBook/v4l/vidioc-qbuf.xml
View File

@ -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>