IPS_CTL
I915_WRITE(IPS_CTL, IPS_ENABLE);
IPS_CTL, IPS_ENABLE, IPS_ENABLE,
IPS_CTL, IPS_ENABLE, 0,
I915_WRITE(IPS_CTL, 0);
POSTING_READ(IPS_CTL);
pipe_config->ips_enabled = I915_READ(IPS_CTL) & IPS_ENABLE;