drm/i915/icl: Fix port B combo PHY context loss after DC transitions

On ICL DMC/PCODE retains the HW context only for port A across DC
transitions, for the other port B combo PHY, it doesn't. So we need to
do this manually after exiting from DC6. Do the reinit even after
exiting from DC5, it won't hurt since we only reinit the PHY in case
it's needed (in case it was disabled to begin with).

As can be guessed from the bugzilla report leaving the PHY uninited will
lead to a later timeout during the port B specific AUX and DDI_IO power
well enabling.

v2:
- Apply the fix on all GEN>=11 platforms. (Rodrigo)

Bspec: 21257
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108070
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181106160621.23057-6-imre.deak@intel.com

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -843,6 +843,14 @@ static void gen9_dc_off_power_well_enable(struct drm_i915_private *dev_priv,
 
 	if (IS_GEN9_LP(dev_priv))
 		bxt_verify_ddi_phy_power_wells(dev_priv);
+
+	if (INTEL_GEN(dev_priv) >= 11)
+		/*
+		 * DMC retains HW context only for port A, the other combo
+		 * PHY's HW context for port B is lost after DC transitions,
+		 * so we need to restore it manually.
+		 */
+		icl_combo_phys_init(dev_priv);
 }
 
 static void gen9_dc_off_power_well_disable(struct drm_i915_private *dev_priv,