BLC_PWM_CTL2
ctl2 = intel_de_read(display, BLC_PWM_CTL2);
intel_de_rmw(display, BLC_PWM_CTL2, BLM_PWM_ENABLE, 0);
ctl2 = intel_de_read(display, BLC_PWM_CTL2);
intel_de_write(display, BLC_PWM_CTL2, ctl2);
intel_de_write(display, BLC_PWM_CTL2, ctl2);
intel_de_posting_read(display, BLC_PWM_CTL2);
intel_de_write(display, BLC_PWM_CTL2, ctl2 | BLM_PWM_ENABLE);