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

[Christoph Mair]

On Wed, Oct 23, 2013 at 1:06 PM, Andreas Kemnade <andreas at kemnade.info> wrote:
> On Mon, 2013-06-24 at 11:38 +0200, Dr. H. Nikolaus Schaller wrote:
>> Hi,
>> fm-radio appears to work. At least on one board (the one where I did solder some wires to measure the clocks and PCM signals).
>> [...]
>> Now comes the bad news: it works only on one GTA04 board and I don't
>> know why it fails on the others I have tested. Since they have no wires I
>> can't check if the clocks are available and the Si47xx is sending PCM
>> to the CPU or not. Or if there is something unreliable in the McBSP config.
>>
>> It could also be some hardware issue. If you look into the schematics, there
>> are series resistors for the McBSP1 interface. Their values are choosen
>> based on the recommendations of a reference design we had found.
>>
>> But 2k2 appears a little high value, taking into account that we have a 2.5 MHz
>> clock. I.e. the signals may be damped and too slow so that e.g. the clocks
>> are not recognized correctly.
>>
> I do not understand the connection here. The McBSP sends out its clocks.
> It should look at the data pin at the right times and interpret whatever
> is avilable there at sampling time if i understand the I2S stuff
> correctly. So we should be able to read some suff and arecord should
> spit out something.

One thing which comes to my mind: did you mux the clock output pin as
input? While this seems wrong, the McBSP needs this configuration to
use its own clock as receive clock. The pin works as output
nonetheless.


> Last time I did some scope measurements i broke my gps antenna connector
> so I am a bit shy now so I hesitate to repeat my scope measurements.

Can you upload your kernel (and if necessary also the userspace
software) somewhere? Then I will do the scope measurements.

Best regards,
  Christoph