Issue 483: fm-demo program does not work in 3.11

Reported by ben deering, Sep 12, 2013

The fm-demo program that was created recently no longer works with 
the latest kernel.  The problem seems to be in the audio side rather 
than in the tuner.  There is a soft hiss from the speakers or 
headphones.  The console reports realistic signal information 
(strong with antenna high, weak with antenna unplugged or low).

Comment 1 by Nikolaus Schaller, Sep 24, 2013

This may not even be a new problem since fm-audio was already weak 
on some GTA04 boards with the 3.7-plus kernel. Maybe, we have a bad 
clock polarity so that data reception depends if changing signals 
are sampled while they change or after they have stabilized. or it 
is a hardware related issue since the coupling resistors have a 
quite high value (2.2 kOhm) and this may damp/slow down the PCM 
digital signals to a level where the OMAP McBSP inputs don't 
recognize them reliably or without jitter.

Labels: Milestone:3.12

Comment 2 by Nikolaus Schaller, May 13, 2017

For a long time we were not even able to use the tuner due to 
strange i2c errors.

This has been fixed with 4.11.

Now we just need to fi the sound card side.

Letux Kernel