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PTN3460 eDP pwm control: not supported?

Question asked by Nikolaus Voss on Aug 30, 2018
Latest reply on Sep 13, 2018 by Nikolaus Voss

Hi,

I want to use pwm brightness control over eDP DPCD register, however the capability registers read:

0x701 = 01

0x702 = 85

which according to the eDP specs means that DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP is set instead of DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP.

Chapter 8.3.2 of datasheet says that

"PWMO pin — the PWM signal generated by PTN3460 based on controls set in
DPCD registers. In addition, PTN3460 can pass through PWM signal from eDP
source as well. Please refer to Ref. 2 for more information."
However, Ref. 2 doesn't clarify this. It seems that PWM pass through is the default. How can I change that?

 

Regards,

Nikolaus Voss

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