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Commit 21636363 authored by Pawel Osciak's avatar Pawel Osciak Committed by Mauro Carvalho Chehab
Browse files

V4L/DVB: Add documentation for the new error flag 



Add documentation for V4L2_BUF_FLAG_ERROR.

Signed-off-by: default avatarPawel Osciak <p.osciak@samsung.com>
Signed-off-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent b2dfd1a4

Documentation/DocBook/v4l/io.xml

+10 −0
Original line number Original line Diff line number Diff line
@@ -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"

They can be both cleared however, then the buffer is in "dequeued"

state, in the application domain to say so.</entry>

state, in the application domain to say so.</entry>

	  </row>

	  </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>

	  <row>

	    <entry><constant>V4L2_BUF_FLAG_KEYFRAME</constant></entry>

	    <entry><constant>V4L2_BUF_FLAG_KEYFRAME</constant></entry>

	    <entry>0x0008</entry>

	    <entry>0x0008</entry>

Documentation/DocBook/v4l/vidioc-qbuf.xml

+12 −2
Original line number Original line Diff line number Diff line
@@ -111,7 +111,11 @@ from the driver's outgoing queue. They just set the 
and <structfield>reserved</structfield>

and <structfield>reserved</structfield>

fields of a &v4l2-buffer; as above, when <constant>VIDIOC_DQBUF</constant>

fields of a &v4l2-buffer; as above, when <constant>VIDIOC_DQBUF</constant>

is called with a pointer to this structure the driver fills the

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

    <para>By default <constant>VIDIOC_DQBUF</constant> blocks when no

buffer is in the outgoing queue. When the

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

	  <para><constant>VIDIOC_DQBUF</constant> failed due to an

internal error. Can also indicate temporary problems like signal

internal error. Can also indicate temporary problems like signal

loss. Note the driver might dequeue an (empty) buffer despite

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>

	</listitem>

      </varlistentry>

      </varlistentry>

    </variablelist>

    </variablelist>