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-rw-r--r--Documentation/DocBook/media/v4l/common.xml10
1 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/DocBook/media/v4l/common.xml b/Documentation/DocBook/media/v4l/common.xml
index 9028721438d..a86f7a04552 100644
--- a/Documentation/DocBook/media/v4l/common.xml
+++ b/Documentation/DocBook/media/v4l/common.xml
@@ -236,7 +236,15 @@ important parts of the API.</para>
<para>The &VIDIOC-QUERYCAP; ioctl is available to check if the kernel
device is compatible with this specification, and to query the <link
linkend="devices">functions</link> and <link linkend="io">I/O
-methods</link> supported by the device. Other features can be queried
+methods</link> supported by the device.</para>
+
+ <para>Starting with kernel version 3.1, VIDIOC-QUERYCAP will return the
+V4L2 API version used by the driver, with generally matches the Kernel version.
+There's no need of using &VIDIOC-QUERYCAP; to check if an specific ioctl is
+supported, the V4L2 core now returns ENOIOCTLCMD if a driver doesn't provide
+support for an ioctl.</para>
+
+ <para>Other features can be queried
by calling the respective ioctl, for example &VIDIOC-ENUMINPUT;
to learn about the number, types and names of video connectors on the
device. Although abstraction is a major objective of this API, the