Sun4i-GPADC causes high system load

[Ryzer]

When testing my most recent builds using the Armbian build framework I found that I was experiencing a constant load greater than 1.00. At first, I thought this is probably normal to have a load during the system boot but after waiting over 10 minutes I found that the load did not decrease. Firstly, I used HTOP but could not find a process that was heavy utilising the CPU with the relative CPU usage show as low. Next I tried using TOP which revealed a process called kworker: freezeable_power. Trying to search for the issue I did not find much until I came across this old forum post that described the same issues I was having:

 

https://forum.armbian.com/topic/7575-k-worker-problem-on-a20-based-boards/page/2/

 

Sure enough, removing the sun4i-gpadc caused the average system load to drop and even relative CPU usage dropped to around 1% utilisation rather than the usual idling around 20 – 25%. The risk is losing the CPU temperature. Following the advice from the latest post I found that setting mode to disabled seemed to do the trick of bringing down the system load while retaining CPU temperature reading. I achieved this by modifying rc.local with the line:

 

Echo disabled > /sys/devices/virtual/thermal/thermal_zone1/mode

 

Admittedly this works reasonably well however it take around approximately 5 minutes for system load to drop down to a more expected 15% - 20% on idle. I am hoping that someone with an understanding of the touchscreen control on the A10/A20 may be able to provide a fix as this out of my depth with my current knowledge.

 

Without rc.local edit:

 

with rc.local edit: