[Letux-kernel] LetuxOS Kernel v5.0-rc1 - BeaglBone backlight issues

H. Nikolaus Schaller hns at goldelico.com
Tue Mar 19 16:35:20 CET 2019


Hi Marek,
I remember that you are an am335x specialist. Do you have an idea how to debug
this issue?

Best regards,
Nikolaus

> Am 19.03.2019 um 16:18 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> 
>> Am 18.03.2019 um 21:04 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> 
>> * BBB+LCDC:	display ok, backlight is always on (but does not respond to "xset dpms")
> 
> This seems to have a threefold reason:
> 1. there is no DT node for connecting the backlight to the panel driver
> 2. the CONFIG_PWM_TIEHRPWM driver is not configured
> 3. after proerly configuring, pwmss_probe() or ehrpwm_pwm_probe() is never called...
>   and the pwm_bl finally fails with EPROBE_DEFER and no /sys/class/backlight is
>   registered.
> 
> The result is that the PWM driver does not run and therefore no backlight pwm driver.
> 
> I now wonder if it ever did work... Probably not...
> 
> BR,
> Nikolaus
> 
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