drm/i915: add port power domains

Parts that poke port specific HW blocks like the encoder HW state
readout or connector hotplug detect code need a way to check whether
required power domains are on or enable/disable these. For this purpose
add a set of power domains that refer to the port HW blocks. Get the
proper port power domains during modeset.

For now when requesting the power domain for a DDI port get it for a 4
lane configuration. This can be optimized later to request only the 2
lane power domain, when proper support is added on the VLV PHY side for
this. Atm, the PHY setup code assumes a 4 lane config in all cases.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -733,6 +733,8 @@ bool intel_crtc_active(struct drm_crtc *crtc);
 void hsw_enable_ips(struct intel_crtc *crtc);
 void hsw_disable_ips(struct intel_crtc *crtc);
 void intel_display_set_init_power(struct drm_i915_private *dev, bool enable);
+enum intel_display_power_domain
+intel_display_port_power_domain(struct intel_encoder *intel_encoder);
 int valleyview_get_vco(struct drm_i915_private *dev_priv);
 void intel_mode_from_pipe_config(struct drm_display_mode *mode,
 				 struct intel_crtc_config *pipe_config);