drm/i915/dp: Factor out intel_dp_get_active_pipes()

Factor out a helper used by a follow up patch to reset an active DP
link.

No functional changes.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510103131.1618266-12-imre.deak@intel.com

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

@@ -4232,9 +4232,9 @@ static bool intel_dp_has_connector(struct intel_dp *intel_dp,
 	return false;
 }
 
-static int intel_dp_prep_link_retrain(struct intel_dp *intel_dp,
-				      struct drm_modeset_acquire_ctx *ctx,
-				      u8 *pipe_mask)
+static int intel_dp_get_active_pipes(struct intel_dp *intel_dp,
+				     struct drm_modeset_acquire_ctx *ctx,
+				     u8 *pipe_mask)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	struct drm_connector_list_iter conn_iter;
@@ -4243,9 +4243,6 @@ static int intel_dp_prep_link_retrain(struct intel_dp *intel_dp,
 
 	*pipe_mask = 0;
 
-	if (!intel_dp_needs_link_retrain(intel_dp))
-		return 0;
-
 	drm_connector_list_iter_begin(&i915->drm, &conn_iter);
 	for_each_intel_connector_iter(connector, &conn_iter) {
 		struct drm_connector_state *conn_state =
@@ -4279,9 +4276,6 @@ static int intel_dp_prep_link_retrain(struct intel_dp *intel_dp,
 	}
 	drm_connector_list_iter_end(&conn_iter);
 
-	if (!intel_dp_needs_link_retrain(intel_dp))
-		*pipe_mask = 0;
-
 	return ret;
 }
 
@@ -4310,13 +4304,19 @@ int intel_dp_retrain_link(struct intel_encoder *encoder,
 	if (ret)
 		return ret;
 
-	ret = intel_dp_prep_link_retrain(intel_dp, ctx, &pipe_mask);
+	if (!intel_dp_needs_link_retrain(intel_dp))
+		return 0;
+
+	ret = intel_dp_get_active_pipes(intel_dp, ctx, &pipe_mask);
 	if (ret)
 		return ret;
 
 	if (pipe_mask == 0)
 		return 0;
 
+	if (!intel_dp_needs_link_retrain(intel_dp))
+		return 0;
+
 	drm_dbg_kms(&dev_priv->drm, "[ENCODER:%d:%s] retraining link\n",
 		    encoder->base.base.id, encoder->base.name);