summaryrefslogtreecommitdiff
path: root/Documentation/DocBook/v4l/dev-radio.xml
diff options
context:
space:
mode:
authorFrederic Weisbecker <fweisbec@gmail.com>2009-10-18 01:09:09 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2009-10-18 01:12:33 +0200
commit0f8f86c7bdd1c954fbe153af437a0d91a6c5721a (patch)
tree94a8d419a470a4f9852ca397bb9bbe48db92ff5c /Documentation/DocBook/v4l/dev-radio.xml
parentdca2d6ac09d9ef59ff46820d4f0c94b08a671202 (diff)
parentf39cdf25bf77219676ec5360980ac40b1a7e144a (diff)
Merge commit 'perf/core' into perf/hw-breakpoint
Conflicts: kernel/Makefile kernel/trace/Makefile kernel/trace/trace.h samples/Makefile Merge reason: We need to be uptodate with the perf events development branch because we plan to rewrite the breakpoints API on top of perf events.
Diffstat (limited to 'Documentation/DocBook/v4l/dev-radio.xml')
-rw-r--r--Documentation/DocBook/v4l/dev-radio.xml57
1 files changed, 57 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/dev-radio.xml b/Documentation/DocBook/v4l/dev-radio.xml
new file mode 100644
index 000000000000..73aa90b45b34
--- /dev/null
+++ b/Documentation/DocBook/v4l/dev-radio.xml
@@ -0,0 +1,57 @@
+ <title>Radio Interface</title>
+
+ <para>This interface is intended for AM and FM (analog) radio
+receivers and transmitters.</para>
+
+ <para>Conventionally V4L2 radio devices are accessed through
+character device special files named <filename>/dev/radio</filename>
+and <filename>/dev/radio0</filename> to
+<filename>/dev/radio63</filename> with major number 81 and minor
+numbers 64 to 127.</para>
+
+ <section>
+ <title>Querying Capabilities</title>
+
+ <para>Devices supporting the radio interface set the
+<constant>V4L2_CAP_RADIO</constant> and
+<constant>V4L2_CAP_TUNER</constant> or
+<constant>V4L2_CAP_MODULATOR</constant> flag in the
+<structfield>capabilities</structfield> field of &v4l2-capability;
+returned by the &VIDIOC-QUERYCAP; ioctl. Other combinations of
+capability flags are reserved for future extensions.</para>
+ </section>
+
+ <section>
+ <title>Supplemental Functions</title>
+
+ <para>Radio devices can support <link
+linkend="control">controls</link>, and must support the <link
+linkend="tuner">tuner or modulator</link> ioctls.</para>
+
+ <para>They do not support the video input or output, audio input
+or output, video standard, cropping and scaling, compression and
+streaming parameter, or overlay ioctls. All other ioctls and I/O
+methods are reserved for future extensions.</para>
+ </section>
+
+ <section>
+ <title>Programming</title>
+
+ <para>Radio devices may have a couple audio controls (as discussed
+in <xref linkend="control" />) such as a volume control, possibly custom
+controls. Further all radio devices have one tuner or modulator (these are
+discussed in <xref linkend="tuner" />) with index number zero to select
+the radio frequency and to determine if a monaural or FM stereo
+program is received/emitted. Drivers switch automatically between AM and FM
+depending on the selected frequency. The &VIDIOC-G-TUNER; or
+&VIDIOC-G-MODULATOR; ioctl
+reports the supported frequency range.</para>
+ </section>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+ -->