drm/i915/adl_s: Update combo PHY master/slave relationships

ADL-S switches up which PHYs are considered a master to other PHYs;
PHY-C is no longer a master, but PHY-D is now.

Bspec: 49291
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Aditya Swarup <aditya.swarup@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210125140753.347998-11-aditya.swarup@intel.com

drivers/gpu/drm/i915/display/intel_combo_phy.c

@@ -246,14 +246,21 @@ static bool phy_is_master(struct drm_i915_private *dev_priv, enum phy phy)
 	 * RKL,DG1:
 	 *   A(master) -> B(slave)
 	 *   C(master) -> D(slave)
+	 * ADL-S:
+	 *   A(master) -> B(slave), C(slave)
+	 *   D(master) -> E(slave)
 	 *
 	 * We must set the IREFGEN bit for any PHY acting as a master
 	 * to another PHY.
 	 */
-	if ((IS_DG1(dev_priv) || IS_ROCKETLAKE(dev_priv)) && phy == PHY_C)
+	if (phy == PHY_A)
 		return true;
+	else if (IS_ALDERLAKE_S(dev_priv))
+		return phy == PHY_D;
+	else if (IS_DG1(dev_priv) || IS_ROCKETLAKE(dev_priv))
+		return phy == PHY_C;
 
-	return phy == PHY_A;
+	return false;
 }
 
 static bool icl_combo_phy_verify_state(struct drm_i915_private *dev_priv,