Re: [PATCH V3 4/5] [Documentation] Media: Update docs for V4L2 FM new features
From: Hans Verkuil
Date: Thu May 03 2012 - 03:24:09 EST
On Wed May 2 2012 23:42:30 manjunatha_halli@xxxxxx wrote:
> From: Manjunatha Halli <x0130808@xxxxxx>
>
> The list of new features -
> 1) New control class for FM RX
> 2) New FM RX CID's - De-Emphasis filter mode and RDS AF switch
> 3) New FM TX CID - RDS Alternate frequency set.
>
> Signed-off-by: Manjunatha Halli <x0130808@xxxxxx>
> ---
> Documentation/DocBook/media/v4l/compat.xml | 3 +
> Documentation/DocBook/media/v4l/controls.xml | 78 ++++++++++++++++++++
> Documentation/DocBook/media/v4l/dev-rds.xml | 5 +-
> .../DocBook/media/v4l/vidioc-g-ext-ctrls.xml | 7 ++
> .../DocBook/media/v4l/vidioc-s-hw-freq-seek.xml | 7 ++-
> 5 files changed, 97 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
> index bce97c5..df1f345 100644
> --- a/Documentation/DocBook/media/v4l/compat.xml
> +++ b/Documentation/DocBook/media/v4l/compat.xml
> @@ -2311,6 +2311,9 @@ more information.</para>
> <para>Added FM Modulator (FM TX) Extended Control Class: <constant>V4L2_CTRL_CLASS_FM_TX</constant> and their Control IDs.</para>
> </listitem>
> <listitem>
> + <para>Added FM Receiver (FM RX) Extended Control Class: <constant>V4L2_CTRL_CLASS_FM_RX</constant> and their Control IDs.</para>
> + </listitem>
> + <listitem>
> <para>Added Remote Controller chapter, describing the default Remote Controller mapping for media devices.</para>
> </listitem>
> </orderedlist>
> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
> index b84f25e..b6e4db2 100644
> --- a/Documentation/DocBook/media/v4l/controls.xml
> +++ b/Documentation/DocBook/media/v4l/controls.xml
> @@ -3018,6 +3018,12 @@ to find receivers which can scroll strings sized as 32 x N or 64 x N characters.
> with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </entry>
> </row>
> <row>
> + <entry spanname="id"><constant>V4L2_CID_RDS_TX_AF_FREQ</constant> </entry>
> + <entry>integer</entry>
> + </row>
> + <row><entry spanname="descr">Sets the RDS Alternate Frequency value which allows a receiver to re-tune to a different frequency providing the same station when the first signal becomes too weak (e.g., when moving out of range). </entry>
> + </row>
> + <row>
> <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_ENABLED</constant> </entry>
> <entry>boolean</entry>
> </row>
> @@ -3146,6 +3152,78 @@ manually or automatically if set to zero. Unit, range and step are driver-specif
> <xref linkend="en50067" /> document, from CENELEC.</para>
> </section>
>
> + <section id="fm-rx-controls">
> + <title>FM Receiver Control Reference</title>
> +
> + <para>The FM Receiver (FM_RX) class includes controls for common features of
> +FM Reception capable devices. Currently this class includes parameter for Alternate
> +frequency.</para>
Remove the last sentence ("Currently this..."). It serves no purpose and would only need
to be updated whenever a control is added.
> +
> + <table pgwide="1" frame="none" id="fm-rx-control-id">
> + <title>FM_RX Control IDs</title>
> +
> + <tgroup cols="4">
> + <colspec colname="c1" colwidth="1*" />
> + <colspec colname="c2" colwidth="6*" />
> + <colspec colname="c3" colwidth="2*" />
> + <colspec colname="c4" colwidth="6*" />
> + <spanspec namest="c1" nameend="c2" spanname="id" />
> + <spanspec namest="c2" nameend="c4" spanname="descr" />
> + <thead>
> + <row>
> + <entry spanname="id" align="left">ID</entry>
> + <entry align="left">Type</entry>
> + </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
> + </row>
> + </thead>
> + <tbody valign="top">
> + <row><entry></entry></row>
> + <row>
> + <entry spanname="id"><constant>V4L2_CID_FM_RX_CLASS</constant> </entry>
> + <entry>class</entry>
> + </row><row><entry spanname="descr">The FM_RX class
> +descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
> +description of this control class.</entry>
> + </row>
> + <row>
> + <entry spanname="id"><constant>V4L2_CID_RDS_AF_SWITCH</constant> </entry>
> + <entry>boolean</entry>
> + </row>
> + <row><entry spanname="descr">Enable/Disable's FM RX RDS Alternate frequency feature. When enabled driver will decode the RDS AF field and tries to switch to this AF frequency once current frequency RSSI level goes below threshold. Value of G_FREQUENCY is unchanged since both original frequency and AF frequency share the same PI code.</entry>
Small improvement: Enable/Disable's -> Enable or Disable the
I'd also remove the "FM RX" part: it's already obvious that we are in the FM RX class of controls.
"When enabled" -> "When enabled the"
"once current" -> once the current"
"below threshold" -> "below the threshold"
I don't understand what you mean with the last sentence: "Value of G_FREQUENCY...".
Shouldn't it be something like:
If the frequency is switched, then &VIDIOC-G-FREQUENCY; will return the new frequency."
> + </row>
> + <row>
> + <entry spanname="id"><constant>V4L2_CID_TUNE_DEEMPHASIS</constant> </entry>
> + <entry>integer</entry>
> + </row>
> + <row id="v4l2-deemphasis"><entry spanname="descr">Configures the de-emphasis value for reception.
> +A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies.
> +Depending on the region, a time constant of either 50 or 75 useconds is used. The enum v4l2_preemphasis
> +defines possible values for pre-emphasis. Here they are:</entry>
> + </row><row>
> + <entrytbl spanname="descr" cols="2">
> + <tbody valign="top">
> + <row>
> + <entry><constant>V4L2_PREEMPHASIS_DISABLED</constant> </entry>
> + <entry>No de-emphasis is applied.</entry>
> + </row>
> + <row>
> + <entry><constant>V4L2_PREEMPHASIS_50_uS</constant> </entry>
> + <entry>A de-emphasis of 50 uS is used.</entry>
> + </row>
> + <row>
> + <entry><constant>V4L2_PREEMPHASIS_75_uS</constant> </entry>
> + <entry>A de-emphasis of 75 uS is used.</entry>
> + </row>
> + </tbody>
> + </entrytbl>
> +
> + </row>
> + <row><entry></entry></row>
> + </tbody>
> + </tgroup>
> + </table>
> +
> + </section>
> <section id="flash-controls">
> <title>Flash Control Reference</title>
>
> diff --git a/Documentation/DocBook/media/v4l/dev-rds.xml b/Documentation/DocBook/media/v4l/dev-rds.xml
> index 38883a4..8188161 100644
> --- a/Documentation/DocBook/media/v4l/dev-rds.xml
> +++ b/Documentation/DocBook/media/v4l/dev-rds.xml
> @@ -55,8 +55,9 @@ If the driver only passes RDS blocks without interpreting the data
> the <constant>V4L2_TUNER_CAP_RDS_BLOCK_IO</constant> flag has to be set. If the
> tuner is capable of handling RDS entities like program identification codes and radio
> text, the flag <constant>V4L2_TUNER_CAP_RDS_CONTROLS</constant> should be set,
> -see <link linkend="writing-rds-data">Writing RDS data</link> and
> -<link linkend="fm-tx-controls">FM Transmitter Control Reference</link>.</para>
> +see <link linkend="writing-rds-data">Writing RDS data</link>,
> +<link linkend="fm-tx-controls">FM Transmitter Control Reference</link>
> +<link linkend="fm-rx-controls">FM Receiver Control Reference</link>.</para>
> </section>
>
> <section id="reading-rds-data">
> diff --git a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
> index b17a7aa..2a8b44e 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
> @@ -258,6 +258,13 @@ These controls are described in <xref
> These controls are described in <xref
> linkend="fm-tx-controls" />.</entry>
> </row>
> + <row>
> + <entry><constant>V4L2_CTRL_CLASS_FM_RX</constant></entry>
> + <entry>0x9c0000</entry>
> + <entry>The class containing FM Receiver (FM RX) controls.
> +These controls are described in <xref
> + linkend="fm-rx-controls" />.</entry>
> + </row>
> <row>
> <entry><constant>V4L2_CTRL_CLASS_FLASH</constant></entry>
> <entry>0x9c0000</entry>
> diff --git a/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml b/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml
> index 18b1a82..c244da9 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml
> @@ -95,7 +95,12 @@ field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
> </row>
> <row>
> <entry>__u32</entry>
> - <entry><structfield>reserved</structfield>[7]</entry>
> + <entry><structfield>fm_band</structfield></entry>
> + <entry>If zero search whole band (from OIRT till Weather if chip supports) else search in a mentioned bands(1=Europe/US, 2=Japan, 3=Russian and 4=Weather band)</entry>
We need proper defines for these bands in linux/videodev2.h! And it also needs
to be properly documented: make a small table as is done for other ioctls as well
and include the official frequency ranges for each.
I also suggest renaming fm_band by just 'band': it might be used for e.g. AM
bands as well in the future (unlikely, but you never know).
Regards,
Hans
> + </row>
> + <row>
> + <entry>__u32</entry>
> + <entry><structfield>reserved</structfield>[6]</entry>
> <entry>Reserved for future extensions. Applications
> must set the array to zero.</entry>
> </row>
>
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