[Gta04-owner] fm-tuner - was Re: hw routing audio patch removed in 3.7?

Andreas Kemnade andreas at kemnade.info
Sat Jun 8 18:58:17 CEST 2013


On Sat, 2013-06-08 at 18:10 +0200, Dr. H. Nikolaus Schaller wrote: 
> Am 08.06.2013 um 18:00 schrieb Benjamin Deering:
> > 
> >> Hmm, so put the conflicting McBSP into the platform data and calling the
> >> tristate function instead of the pinmux thing? That is no twl4030
> >> specific code, so somehow it still feels a bit strange to have it there.
> >> But using a tristate function is a step forward.
> >> 
> >> Greetings
> >> Andreas Kemnade
> > Is the change needed to enable audio from the FM tuner chip similar to the gsm HW routing issue?
> No, there is no direct connection ("hardware routing") between the FM chip and the Audio Codec (TPS65950) so that it needs CPU support.
> > 
> > I have your userspace hack from here: 
> > http://misc.andi.de1.cc/si4721.c, 
> Oh that is cool!
> > it shows that it is finding a station, but nothing I can do in the mixer gets audio.
> What it needs is some arecord | aplayer pipeline through the CPU similar to the /root/dial [1] script but reading a different McBSP / ALSA "sound card".
> But even then it is not clear if that works. AFAIK nobody was able yet to test this digital sound interface. So there may be driver issues, configuration issues (e.g. PCM format and clock rate) and I even can't exclude hardware issues (someone told me a while ago that the interface resistors may be wrongly choosen although they match some recommendation from Silicon Labs).
ok, lets summarize what i have seen.
Signals at McBSP1 look fine. I was able to add a sound card to send out
data to McBSP1. McBSP1 is master. I was never able to get any data from
McBSP1. Since McBSP1 is master, it should always get data, since it
generates the clock by itself. When recording data, the clocks are

I also played somehow with setting another McBSP to master mode (I guess
I tristated the twl4030 for that and used the corresponding McBSP) and i
got (crappy) data. And then i just changed the MCBSP number and... no

I asked in linux-omap about that, got one hint, but that did not help
and also nobody seems to use McBSP1 in master mode.

Andreas Kemnade

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