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>
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@ -701,6 +701,16 @@ buffer cannot be on both queues at the same time, the
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They can be both cleared however, then the buffer is in "dequeued"
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state, in the application domain to say so.</entry>
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</row>
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<row>
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<entry><constant>V4L2_BUF_FLAG_ERROR</constant></entry>
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<entry>0x0040</entry>
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<entry>When this flag is set, the buffer has been dequeued
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successfully, although the data might have been corrupted.
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This is recoverable, streaming may continue as normal and
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the buffer may be reused normally.
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Drivers set this flag when the <constant>VIDIOC_DQBUF</constant>
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ioctl is called.</entry>
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</row>
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<row>
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<entry><constant>V4L2_BUF_FLAG_KEYFRAME</constant></entry>
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<entry>0x0008</entry>
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@ -111,7 +111,11 @@ from the driver's outgoing queue. They just set the
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and <structfield>reserved</structfield>
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fields of a &v4l2-buffer; as above, when <constant>VIDIOC_DQBUF</constant>
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is called with a pointer to this structure the driver fills the
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remaining fields or returns an error code.</para>
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remaining fields or returns an error code. The driver may also set
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<constant>V4L2_BUF_FLAG_ERROR</constant> in the <structfield>flags</structfield>
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field. It indicates a non-critical (recoverable) streaming error. In such case
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the application may continue as normal, but should be aware that data in the
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dequeued buffer might be corrupted.</para>
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<para>By default <constant>VIDIOC_DQBUF</constant> blocks when no
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buffer is in the outgoing queue. When the
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@ -158,7 +162,13 @@ enqueue a user pointer buffer.</para>
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<para><constant>VIDIOC_DQBUF</constant> failed due to an
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internal error. Can also indicate temporary problems like signal
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loss. Note the driver might dequeue an (empty) buffer despite
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returning an error, or even stop capturing.</para>
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returning an error, or even stop capturing. Reusing such buffer may be unsafe
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though and its details (e.g. <structfield>index</structfield>) may not be
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returned either. It is recommended that drivers indicate recoverable errors
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by setting the <constant>V4L2_BUF_FLAG_ERROR</constant> and returning 0 instead.
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In that case the application should be able to safely reuse the buffer and
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continue streaming.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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