A few minor corrections here. jon On Thu, 28 May 2015 18:49:18 -0300 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> wrote: > Make the text clearer about what the properties API does. > > Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> > > diff --git a/Documentation/DocBook/media/dvb/dvbproperty.xml b/Documentation/DocBook/media/dvb/dvbproperty.xml > index 28ea62067af6..c10ed0636d02 100644 > --- a/Documentation/DocBook/media/dvb/dvbproperty.xml > +++ b/Documentation/DocBook/media/dvb/dvbproperty.xml > @@ -1,8 +1,35 @@ > -<section id="FE_GET_SET_PROPERTY"> > -<title><constant>FE_GET_PROPERTY/FE_SET_PROPERTY</constant></title> > -<para>This section describes the DVB version 5 extension of the DVB-API, also > -called "S2API", as this API were added to provide support for DVB-S2. It was > -designed to be able to replace the old frontend API. Yet, the DISEQC and > +<section id="frontend-properties"> > +<title>DVB Frontend properties</title> > +<para>Tuning into a Digital TV physical channel and starting decoding it > + requires to change a set of parameters, in order to control the requires *changing* as set... > + tuner, the demodulator, the Linear Low-noise Amplifier (LNA) and to set the > + antena subsystem via Satellite Equipment Control (SEC), on satellital antenna > + systems. The actual parameters are specific to each particular digital > + TV standards, and may change as the digital TV specs evolutes.</para> standard (no "s"). s/evolutes/evolves/ > +<para>In the past, the strategy used were to have an union with the parameters s/were to have an/was to have a/ > + needed to tune for DVB-S, DVB-C, DVB-T and ATSC delivery systems grouped > + there. The problem is that, as the second generation standards appeared, > + those structs were not big enough to contain the additional parameters. > + Also, the union didn't have any space left to be expanded without breaking > + userspace. So, the decision was to deprecate the legacy union/struct based > + approach, in favor of a properties set approach.</para> > +<para>By using a properties set, it is now possible to extend and support any > + digital TV without needing to redesign the API</para> > +<para>Example: with the properties based approach, in order to set the tuner > + to a DVB-C channel at 651 kHz, modulated with 256-QAM, FEC 3/4 and symbol > + rate of 5.217 Mbauds, those properties should be sent to > + <link linkend="FE_GET_PROPERTY"><constant>FE_SET_PROPERTY</constant></link> ioctl:</para> > + <itemizedlist> > + <listitem>DTV_FREQUENCY = 651000000</listitem> > + <listitem>DTV_MODULATION = QAM_256</listitem> > + <listitem>DTV_INVERSION = INVERSION_AUTO</listitem> > + <listitem>DTV_SYMBOL_RATE = 5217000</listitem> > + <listitem>DTV_INNER_FEC = FEC_3_4</listitem> > + <listitem>DTV_TUNE</listitem> > + </itemizedlist> > +<para>NOTE: This section describes the DVB version 5 extension of the DVB-API, > +also called "S2API", as this API were added to provide support for DVB-S2. It > +was designed to be able to replace the old frontend API. Yet, the DISEQC and > the capability ioctls weren't implemented yet via the new way.</para> > <para>The typical usage for the <constant>FE_GET_PROPERTY/FE_SET_PROPERTY</constant> > API is to replace the ioctl's were the <link linkend="dvb-frontend-parameters"> jon -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
