[Gta04-owner] headset detection/twl4030 madc issue?

Benjamin Deering ben_deering at swissmail.org
Sat Nov 16 14:13:42 CET 2013

While trying to figure out the issue with headset detection in 3.11 and 
3.12 kernels I noticed that I am not getting reasonable values from the 
micsense adc.

cat /sys/devices/platform/twl4030_madc_hwmon/in7_input

On a 3.7 kernel I get ~20 unplugged and ~820 with my headphones plugged 
in.  I am getting ~830 always with 3.12.  The number changes (828, 833, 
830) so it is doing a read.  I tried increasing the timeout in 

timeout = 1 + jiffies + msecs_to_jiffies(timeout_ms);

but it made no difference, I think timeouts would have shown up in the logs.

I looked at the schematics to see what the other ADC channels were 
connected to.  It looks like (non-existant) light sensor on in6_input?  
in8_input jumps from ~2000 to ~5000 is usb is connected.  I don't know 
what expected values would be on the other channels to test.

Is there some supply voltage that isn't being provided to micsense, or 
some misconfiguration in the twl4030-madc?  I will keep looking, but 
maybe someone will know right away.


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