PXA PWM possible regression after 3.5: backlight remains off after resume

Robert Jarzmik robert.jarzmik at free.fr
Tue Sep 25 15:43:39 EDT 2012

Paul Parsons <lost.distance at yahoo.com> writes:

> The same failure is also present in 3.6-rc1.
> Just to be clear, are you saying that drivers/pwm/pwm-pxa.c should
> include suspend/resume handlers like in drivers/pwm/pwm-samsung.c ?
> Agreed that it is possible that recent changes exposed a latent bug
> somewhere, and that turning the backlight on after resume should never
> have worked.

Hi Paul,

I checked on the mioa701 board (see [1]).
On my board, the backlight if fully driven by PXA PWM0, and the suspend/resume
is working perfectly.

So I don't thing anything is needed for suspend/resume wrt PWM (empirically).



$ cat /sys/class/backlight/pwm-backlight/actual_brightness 
$ cat /sys/class/backlight/pwm-backlight/actual_brightness 
$ echo 90 > /sys/class/backlight/pwm-backlight/brightness        
$ echo mem > /sys/power/state 
$ cat /sys/class/backlight/pwm-backlight/actual_brightness 
$ uname -a
Linux mioa701 3.6.0-rc6+ #26 PREEMPT Sat Sep 22 22:08:41 CEST 2012 armv5tel unknown

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