> Em 03-12-2010 10:50, manjunatha_halli@xxxxxx escreveu: > > From: Manjunatha Halli <manjunatha_halli@xxxxxx> > > > > Added entries for following 2 new CID's which are added for TI FM > > driver: > > - V4L2_CID_RSSI_THRESHOLD > > - V4L2_CID_TUNE_AF > > > > Signed-off-by: Manjunatha Halli <manjunatha_halli@xxxxxx> > > --- > > Documentation/DocBook/v4l/controls.xml | 12 ++++++++++++ > > 1 files changed, 12 insertions(+), 0 deletions(-) > > > > diff --git a/Documentation/DocBook/v4l/controls.xml b/Documentation/DocBook/v4l/controls.xml > > index 2fae3e8..b560953 100644 > > --- a/Documentation/DocBook/v4l/controls.xml > > +++ b/Documentation/DocBook/v4l/controls.xml > > @@ -132,6 +132,18 @@ consumption state.</entry> > > <entry>Loudness mode (bass boost).</entry> > > </row> > > <row> > > + <entry><constant>V4L2_CID_RSSI_THRESHOLD</constant></entry> > > + <entry>integer</entry> > > + <entry>Set RSSI threshold level. Change the default threshold > > +level used to select valid frequencies during vidioc_s_hw_freq_seek.</entry> > > + </row> > > + <row> > > + <entry><constant>V4L2_CID_TUNE_AF</constant></entry> > > + <entry>integer</entry> > > + <entry>Set Alternative Frequency mode. Enable or disable > > +alternative frequency mode.</entry> > > + </row> > > + <row> > > <entry><constant>V4L2_CID_BLACK_LEVEL</constant></entry> > > <entry>integer</entry> > > <entry>Another name for brightness (not a synonym of > > Sorry, but, I doubt that any userspace application developer will find those descriptions > useful. > > For the threshold: I understand that this is the carrier strength used to detect a > channel, right? If so, please improve the description. > Also, The better is to associate its scale to a carrier level in some unit like dB. Hi Mauro and Manjunatha, >From my recollection of 3GPP (which is obviously not FM radio), the requirements on a RSSI are intentionally loose. The "I" in RSSI is for "indicator", not a precise quantity. An example RSSI measurement specification can be found here: ftp://ftp.3gpp.org/specs/2010-09/Rel-9/25_series/25215-920.zip (I couldn't find an RSSI spec for FM radio.) In 3GPP, RSSI is used for Human-Machine interfaces: e.g. How many bars are shown on your phone's display. Applications can also use it to decide if they have sufficient signal or not. I don't think standardizing the units into dB is going to be useful for applications. RSSI measurements from different FM receiver hardware cannot be fairly compared using standard units, since not all FM receivers will be creating a RSSI value in the same way. However, standardizing the range of the scale for this control would be useful for applications. I don't care if drivers use a scale of 0-100, 0-255 (like this patchset), or 0-65535. I just suggest that all drivers, that provide this process-decision threshold-control, use the same range. My $0.02. > The second control means absolutely nothing... It is not a boolean value, and what > is "alternative" frequency mode? I agree with Mauro here. The documentation does not give any idea what alternate frequency means to an application developer who does not already know about the underlying hardware receiver. Regards, Andy -- 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
