[pvrusb2] pvrusb2-mci-20070114 radio support - stereo?

Mike Isely isely at isely.net
Sat Jan 20 11:38:50 CST 2007

On Sat, 20 Jan 2007, Hans Verkuil wrote:

> On Saturday 20 January 2007 05:17, Mike Isely wrote:
> > Got it!  I've got stereo FM radio working now.  The root cause was a
> > VIDIOC_S_TUNER command (which carried instructions to switch to
> > stereo mode) which wasn't making it to the tuner core.
> >
> > A new snapshot will be forthcoming.
> Mike, 
> Is this a change that is also relevant for ivtv?

Hans:  If you're broadcasting VIDIOC_S_TUNER to all I2C client modules, 
then ivtv is fine in this regard.  I wasn't doing this (I thought I was 
but I wasn't).

> I also noticed in tuner-core.c that audmode is used for both radio and 
> TV tuner. I think that this should be split into a radio_audmode and a 
> tv_audmode field.

Yes, that realization is what caused me to look for this.  When in radio 
mode, it's the tuner that cares about the audio mode, while in tv mode 
it's the audio chip that cares about the audio mode.

As for splitting the control, I'm not sure if it is really needed.  As 
has been driven into my head on multiple occassions, the V4L 
architecture with respect to handling all manner of controls is a 
collective thing.  We're not supposed to care who wants to see what 
command.  We send the commands everywhere and it's up to each module to 
react appropriately.  There logically really is only "one" audio mode; 
it's just that the handling of it moves between I2C client modules 
depending on the tuner mode.


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