AnsweredAssumed Answered

pwm on nitrogen6x or sabrelite

Question asked by Kyle Johnson on Feb 13, 2014
Latest reply on Feb 13, 2014 by Eric Nelson


We have been experiencing a small but important issue with our IMX6.  I would greatly appreciate any advice you had for me on how to go about fixing it.

There are two related parts to the problem:

1) Approximately, five minutes after the IMX boots up it seems to go into some kind of sleep mode.  Specifically, the backlight (a PWM which we are using to drive our motors) powers down and we lose our ability to control the PWM (normally we control this through interacting with the backlight brightness file found at /sys/class/backlight/pwm-backlight.(0/4)/brightness).

As the IMX is designed for smart devices such as tablets, this is obviously considered a feature under most applications, however, we need it to not go to sleep ever.  Can you tell me how to disable this feature? Thanks.

2) The other problem is very similar when ever we do write to the brightness file (/sys/class/backlight/pwm-backlight.(0/4)/brightness).  It prints out the following line:

pwm_config: pwm freq = 20000, clk_select=2 clock_rate=22000000

pwm_config: pwm freq = 32786, clk_select=2 clock_rate=22000000

Every time that we right to the brightness file it prints this out.  Which, since we are frequently writing to this file that ends up being a lot of time consuming print outs.  I would like to be able to stop this file from printing these lines.  Could you suggest how we might disable this as well? 

Thank you so much for all your help.