BLC_PWM_CTL
ctl = intel_de_read(display, BLC_PWM_CTL);
ctl = intel_de_read(display, BLC_PWM_CTL);
val = intel_de_read(display, BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
tmp = intel_de_read(display, BLC_PWM_CTL) & ~mask;
intel_de_write(display, BLC_PWM_CTL, tmp | level);
ctl = intel_de_read(display, BLC_PWM_CTL);
intel_de_write(display, BLC_PWM_CTL, 0);
intel_de_write(display, BLC_PWM_CTL, ctl);
intel_de_posting_read(display, BLC_PWM_CTL);
intel_de_write(display, BLC_PWM_CTL, ctl);