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authorMauro Carvalho Chehab <mchehab@redhat.com>2011-06-25 14:11:52 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-07-27 17:53:16 -0300
commitc20eb18ce1db6792db69f0574f7e955e9f92a213 (patch)
tree2dd4b7aae9a3b18a0d01652a61090f637fe4289d /Documentation/DocBook/media/v4l
parent29834c1ac7589c72996c5d02349d63fd397ef131 (diff)
[media] DocBook/v4l: Document the new system-wide version behavior
Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/media/v4l')
-rw-r--r--Documentation/DocBook/media/v4l/common.xml10
-rw-r--r--Documentation/DocBook/media/v4l/v4l2.xml6
-rw-r--r--Documentation/DocBook/media/v4l/vidioc-querycap.xml15
3 files changed, 24 insertions, 7 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
diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index a7fd76d0dac..c5ee3982cff 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -128,6 +128,12 @@ structs, ioctls) must be noted in more detail in the history chapter
applications. -->
<revision>
+ <revnumber>3.1</revnumber>
+ <date>2011-06-27</date>
+ <authorinitials>mcc, po</authorinitials>
+ <revremark>Documented that VIDIOC_QUERYCAP now returns a per-subsystem version instead of a per-driver one.</revremark>
+ </revision>
+ <revision>
<revnumber>2.6.39</revnumber>
<date>2011-03-01</date>
<authorinitials>mcc, po</authorinitials>
diff --git a/Documentation/DocBook/media/v4l/vidioc-querycap.xml b/Documentation/DocBook/media/v4l/vidioc-querycap.xml
index f29f1b86213..7aa697323c7 100644
--- a/Documentation/DocBook/media/v4l/vidioc-querycap.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-querycap.xml
@@ -67,9 +67,8 @@ driver is not compatible with this specification the ioctl returns an
<entry><para>Name of the driver, a unique NUL-terminated
ASCII string. For example: "bttv". Driver specific applications can
use this information to verify the driver identity. It is also useful
-to work around known bugs, or to identify drivers in error reports.
-The driver version is stored in the <structfield>version</structfield>
-field.</para><para>Storing strings in fixed sized arrays is bad
+to work around known bugs, or to identify drivers in error reports.</para>
+<para>Storing strings in fixed sized arrays is bad
practice but unavoidable here. Drivers and applications should take
precautions to never read or write beyond the end of the array and to
make sure the strings are properly NUL-terminated.</para></entry>
@@ -100,9 +99,13 @@ empty string (<structfield>bus_info</structfield>[0] = 0).<!-- XXX pci_dev->slot
<row>
<entry>__u32</entry>
<entry><structfield>version</structfield></entry>
- <entry><para>Version number of the driver. Together with
-the <structfield>driver</structfield> field this identifies a
-particular driver. The version number is formatted using the
+ <entry><para>Version number of the driver.</para>
+<para>Starting on kernel 3.1, the version reported is provided per
+V4L2 subsystem, following the same Kernel numberation scheme. However, it
+should not always return the same version as the kernel, if, for example,
+an stable or distribution-modified kernel uses the V4L2 stack from a
+newer kernel.</para>
+<para>The version number is formatted using the
<constant>KERNEL_VERSION()</constant> macro:</para></entry>
</row>
<row>