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authorHans Verkuil <hverkuil@xs4all.nl>2010-09-11 11:38:51 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2010-10-21 01:05:56 -0200
commit6756207a71a0f976ab027186d0966a2162aaf922 (patch)
treeb86d48d98e27d25b313be6759aabde5c81a640c3 /Documentation/DocBook/v4l
parent0827d0664dfa046dc9359c1a45f613d916431ed7 (diff)
V4L/DVB: V4L Doc: correct the documentation for VIDIOC_QUERYMENU
The VIDIOC_QUERYMENU documentation was not correct. EINVAL can be returned if the driver does not support some of the menu items. I.e. in a list of MPEG bitrates a driver generally supports only a subset of these. This behavior has been in place for years, but was never properly documented. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/v4l')
-rw-r--r--Documentation/DocBook/v4l/controls.xml3
-rw-r--r--Documentation/DocBook/v4l/vidioc-queryctrl.xml18
2 files changed, 12 insertions, 9 deletions
diff --git a/Documentation/DocBook/v4l/controls.xml b/Documentation/DocBook/v4l/controls.xml
index 68c83449d7c..2fae3e87ce7 100644
--- a/Documentation/DocBook/v4l/controls.xml
+++ b/Documentation/DocBook/v4l/controls.xml
@@ -364,9 +364,6 @@ enumerate_menu (void)
querymenu.index++) {
if (0 == ioctl (fd, &VIDIOC-QUERYMENU;, &amp;querymenu)) {
printf (" %s\n", querymenu.name);
- } else {
- perror ("VIDIOC_QUERYMENU");
- exit (EXIT_FAILURE);
}
}
}
diff --git a/Documentation/DocBook/v4l/vidioc-queryctrl.xml b/Documentation/DocBook/v4l/vidioc-queryctrl.xml
index 8e0e055ac93..0d5e8283cf3 100644
--- a/Documentation/DocBook/v4l/vidioc-queryctrl.xml
+++ b/Documentation/DocBook/v4l/vidioc-queryctrl.xml
@@ -103,8 +103,12 @@ structure. The driver fills the rest of the structure or returns an
<structfield>index</structfield> is invalid. Menu items are enumerated
by calling <constant>VIDIOC_QUERYMENU</constant> with successive
<structfield>index</structfield> values from &v4l2-queryctrl;
-<structfield>minimum</structfield> (0) to
-<structfield>maximum</structfield>, inclusive.</para>
+<structfield>minimum</structfield> to
+<structfield>maximum</structfield>, inclusive. Note that it is possible
+for <constant>VIDIOC_QUERYMENU</constant> to return an &EINVAL; for some
+indices between <structfield>minimum</structfield> and <structfield>maximum</structfield>.
+In that case that particular menu item is not supported by this driver. Also note that
+the <structfield>minimum</structfield> value is not necessarily 0.</para>
<para>See also the examples in <xref linkend="control" />.</para>
@@ -139,7 +143,7 @@ string. This information is intended for the user.</entry>
<entry><structfield>minimum</structfield></entry>
<entry>Minimum value, inclusive. This field gives a lower
bound for <constant>V4L2_CTRL_TYPE_INTEGER</constant> controls and the
-lowest valid index (always 0) for <constant>V4L2_CTRL_TYPE_MENU</constant> controls.
+lowest valid index for <constant>V4L2_CTRL_TYPE_MENU</constant> controls.
For <constant>V4L2_CTRL_TYPE_STRING</constant> controls the minimum value
gives the minimum length of the string. This length <emphasis>does not include the terminating
zero</emphasis>. It may not be valid for any other type of control, including
@@ -279,7 +283,7 @@ values which are actually different on the hardware.</entry>
</row>
<row>
<entry><constant>V4L2_CTRL_TYPE_MENU</constant></entry>
- <entry>0</entry>
+ <entry>&ge; 0</entry>
<entry>1</entry>
<entry>N-1</entry>
<entry>The control has a menu of N choices. The names of
@@ -405,8 +409,10 @@ writing a value will cause the device to carry out a given action
<term><errorcode>EINVAL</errorcode></term>
<listitem>
<para>The &v4l2-queryctrl; <structfield>id</structfield>
-is invalid. The &v4l2-querymenu; <structfield>id</structfield> or
-<structfield>index</structfield> is invalid.</para>
+is invalid. The &v4l2-querymenu; <structfield>id</structfield> is
+invalid or <structfield>index</structfield> is out of range (less than
+<structfield>minimum</structfield> or greater than <structfield>maximum</structfield>)
+or this particular menu item is not supported by the driver.</para>
</listitem>
</varlistentry>
<varlistentry>