[media] V4L2: Add per-device-node capabilities
If V4L2_CAP_DEVICE_CAPS is set, then the new device_caps field is filled with
the capabilities of the opened device node.
The capabilities field traditionally contains the capabilities of the physical
device, being a superset of all capabilities available at the several device
nodes. E.g., if you open /dev/video0, then if it contains VBI caps then that means
that there is a corresponding vbi node as well. And the capabilities field of
both the video and vbi nodes should contain identical caps.
However, it would be very useful to also have a capabilities field that contains
just the caps for the currently open device, hence the new CAP bit and field.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index c736380..c93298f 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2393,6 +2393,10 @@
to the <link linkend="control">User controls class</link>.
</para>
</listitem>
+ <listitem>
+ <para>Added the device_caps field to struct v4l2_capabilities and added the new
+ V4L2_CAP_DEVICE_CAPS capability.</para>
+ </listitem>
</orderedlist>
</section>
diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index e97c512..dce3fef 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -128,6 +128,13 @@
applications. -->
<revision>
+ <revnumber>3.3</revnumber>
+ <date>2012-01-11</date>
+ <authorinitials>hv</authorinitials>
+ <revremark>Added device_caps field to struct v4l2_capabilities.</revremark>
+ </revision>
+
+ <revision>
<revnumber>3.2</revnumber>
<date>2011-08-26</date>
<authorinitials>hv</authorinitials>
@@ -417,7 +424,7 @@
</partinfo>
<title>Video for Linux Two API Specification</title>
- <subtitle>Revision 3.2</subtitle>
+ <subtitle>Revision 3.3</subtitle>
<chapter id="common">
&sub-common;
diff --git a/Documentation/DocBook/media/v4l/vidioc-querycap.xml b/Documentation/DocBook/media/v4l/vidioc-querycap.xml
index e3664d6..4643505 100644
--- a/Documentation/DocBook/media/v4l/vidioc-querycap.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-querycap.xml
@@ -124,12 +124,35 @@
<row>
<entry>__u32</entry>
<entry><structfield>capabilities</structfield></entry>
- <entry>Device capabilities, see <xref
- linkend="device-capabilities" />.</entry>
+ <entry>Available capabilities of the physical device as a whole, see <xref
+ linkend="device-capabilities" />. The same physical device can export
+ multiple devices in /dev (e.g. /dev/videoX, /dev/vbiY and /dev/radioZ).
+ The <structfield>capabilities</structfield> field should contain a union
+ of all capabilities available around the several V4L2 devices exported
+ to userspace.
+ For all those devices the <structfield>capabilities</structfield> field
+ returns the same set of capabilities. This allows applications to open
+ just one of the devices (typically the video device) and discover whether
+ video, vbi and/or radio are also supported.
+ </entry>
</row>
<row>
<entry>__u32</entry>
- <entry><structfield>reserved</structfield>[4]</entry>
+ <entry><structfield>device_caps</structfield></entry>
+ <entry>Device capabilities of the opened device, see <xref
+ linkend="device-capabilities" />. Should contain the available capabilities
+ of that specific device node. So, for example, <structfield>device_caps</structfield>
+ of a radio device will only contain radio related capabilities and
+ no video or vbi capabilities. This field is only set if the <structfield>capabilities</structfield>
+ field contains the <constant>V4L2_CAP_DEVICE_CAPS</constant> capability.
+ Only the <structfield>capabilities</structfield> field can have the
+ <constant>V4L2_CAP_DEVICE_CAPS</constant> capability, <structfield>device_caps</structfield>
+ will never set <constant>V4L2_CAP_DEVICE_CAPS</constant>.
+ </entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>reserved</structfield>[3]</entry>
<entry>Reserved for future extensions. Drivers must set
this array to zero.</entry>
</row>
@@ -276,6 +299,13 @@
<entry>The device supports the <link
linkend="mmap">streaming</link> I/O method.</entry>
</row>
+ <row>
+ <entry><constant>V4L2_CAP_DEVICE_CAPS</constant></entry>
+ <entry>0x80000000</entry>
+ <entry>The driver fills the <structfield>device_caps</structfield>
+ field. This capability can only appear in the <structfield>capabilities</structfield>
+ field and never in the <structfield>device_caps</structfield> field.</entry>
+ </row>
</tbody>
</tgroup>
</table>