[Gta04-owner] first tries with si4721

Andreas Kemnade andreas at kemnade.info
Sat Feb 11 13:34:35 CET 2012


Hi,

On Fri, 2012-02-10 at 09:10 +0100, Dr. H. Nikolaus Schaller wrote:
> Am 09.02.2012 um 22:30 schrieb Andreas Kemnade:
> 
> > Hi,
> > 
> > I played a bit with the si4721 from userspace using /dev/i2c-2. According
> > to SNR/RSSI values it seems to find something.
> > 
> > Now I am wondering how I can hear that.
> > In 2.6.32 arecord -l does not list a gta04fm pcm
> > aplay -l does
> > 
> > What needs to be done there? That's not a part of the kernel
> > I know well. Is the clock really from the si4721? 
> 
> Well, the ALSA driver is just a stub that compiles and presents
> some more or less useful interface.
> 
> The driver for the PCM interface to the Si47xx is here
> 
> 	https://github.com/goldelico/gta04-kernel/blob/hw-validation/sound/soc/omap/gta04-fm.c
> 
> And the ALSA driver here:
> 
> 	https://github.com/goldelico/gta04-kernel/blob/hw-validation/sound/soc/codecs/si47xx.c
> 

I have already seen these files but I have not understood why I have no
capture interface. After learning a lot about the alsa code, I finally
understand something more and after some sleep I found this nonsense:
(from si47xx.c)
	.playback = {
		.stream_name = "Capture",

I guess now I understand why I have no capture interface. That has taken
a lot of time to understand that simple think.

> They do not initialize much more than the McBSP link.
> And they do not define amixer capabilities like recording or play back volume etc.
> 
> > I understand the datasheet so that the clock comes from host.
> 
> If I remember correctly, this is a parameter of the McBSP interface
> and can be defined in the gta04-fm.c source where the setup of
> the DAI link is done.

I try to get the DAI link working now as a first step.

Greetings
Andreas Kemnade




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