Hello Wolfgang, On 21.04.20 16:50, Wolfgang Kamp - datakamp wrote: > I found out that the panel backlight enable function in libgfxinit for > Broxton platform (Intel x5-E3940) will not work for me. > The Backlight Enabling Sequence Description in the Intel document Doc Ref # > IHD-OS-BXT-Vol 7-05.17 says: > 1. Set frequency and duty cycle in BLC_PWM_FREQ Frequency and BLC_PWM_DUTY > Duty Cycle. > 2. Enable PWM output and set polarity in BLC_PWM_CTL PWM Enable and PWM > Polarity.
> It is also necessary to set Bit 2 in the PP_CONTROL register to "1" to enable > Backlight Power. did you confirm this additional step by testing? I have only tested one board so far. It uses the second set of panel registers and I can control the PWM output just fine _without_ touching PP_CONTROL. > > In "hw-gfx-gma-panel.adb" in the function Backlight_On only > BXT_BLC_PWM_CTL_ENABLE will be set and PP_CONTROL setting is excluded through > the If statement. > Also I can't find any call of the Set_Backlight function and I'm missing the > setting of the PWM frequency divider in this function. Most panels will work > with 200Hz PWM. `libgfxinit` is not designed as firmware and expects that board/panel specific settings are already performed by the firmware. I have just pushed a patch [1] to add the missing configuration in coreboot. It needs to be configured in the devicetree. Hope that helps, Nico [1] https://review.coreboot.org/c/coreboot/+/40694 _______________________________________________ coreboot mailing list -- coreboot@coreboot.org To unsubscribe send an email to coreboot-le...@coreboot.org
