Hello,
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.
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. Can anyone help?
Kind regards, Wolfgang Kamp