drm/i915/dp: Use check link state work in the detect handler

Simplify things by retraining a DP link if a bad link is detected in the
connector detect handler from the encoder's check link state work,
similarly to how this is done after a modeset link training failure.

v2: Add TODO: comment to remove the detect-time link state check.
    (Ville)

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/20240610164933.2947366-13-imre.deak@intel.com

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

@@ -5169,8 +5169,8 @@ static bool intel_dp_is_connected(struct intel_dp *intel_dp)
 		intel_dp->is_mst;
 }
 
-int intel_dp_retrain_link(struct intel_encoder *encoder,
-			  struct drm_modeset_acquire_ctx *ctx)
+static int intel_dp_retrain_link(struct intel_encoder *encoder,
+				 struct drm_modeset_acquire_ctx *ctx)
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
@@ -5904,12 +5904,13 @@ intel_dp_detect(struct drm_connector *connector,
 	/*
 	 * Some external monitors do not signal loss of link synchronization
 	 * with an IRQ_HPD, so force a link status check.
+	 *
+	 * TODO: this probably became redundant, so remove it: the link state
+	 * is rechecked/recovered now after modesets, where the loss of
+	 * synchronization tends to occur.
 	 */
-	if (!intel_dp_is_edp(intel_dp)) {
-		ret = intel_dp_retrain_link(encoder, ctx);
-		if (ret)
-			return ret;
-	}
+	if (!intel_dp_is_edp(intel_dp))
+		intel_dp_check_link_state(intel_dp);
 
 	/*
 	 * Clearing NACK and defer counts to get their exact values

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

@@ -57,8 +57,6 @@ void intel_dp_set_link_params(struct intel_dp *intel_dp,
 int intel_dp_get_active_pipes(struct intel_dp *intel_dp,
 			      struct drm_modeset_acquire_ctx *ctx,
 			      u8 *pipe_mask);
-int intel_dp_retrain_link(struct intel_encoder *encoder,
-			  struct drm_modeset_acquire_ctx *ctx);
 void intel_dp_link_check(struct intel_encoder *encoder);
 void intel_dp_check_link_state(struct intel_dp *intel_dp);
 void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode);