drm/i915/mst: abstract intel_dp_ack_sink_irq_esi()

Smaller functions make the thing easier to read. Debug log failures to
ack.

Note: Looks like we have the retry loop simply because of hysterical
raisins, dating back to the original DP MST enabling. Keep it, though I
have no idea why we have it.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220112110319.1172110-2-jani.nikula@intel.com

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

@@ -2821,6 +2821,19 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
 		DP_DPRX_ESI_LEN;
 }
 
+static bool intel_dp_ack_sink_irq_esi(struct intel_dp *intel_dp, u8 esi[4])
+{
+	int retry;
+
+	for (retry = 0; retry < 3; retry++) {
+		if (drm_dp_dpcd_write(&intel_dp->aux, DP_SINK_COUNT_ESI + 1,
+				      &esi[1], 3) == 3)
+			return true;
+	}
+
+	return false;
+}
+
 bool
 intel_dp_needs_vsc_sdp(const struct intel_crtc_state *crtc_state,
 		       const struct drm_connector_state *conn_state)
@@ -3661,7 +3674,6 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
 		 */
 		u8 esi[DP_DPRX_ESI_LEN+2] = {};
 		bool handled;
-		int retry;
 
 		if (!intel_dp_get_sink_irq_esi(intel_dp, esi)) {
 			drm_dbg_kms(&i915->drm,
@@ -3686,15 +3698,8 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
 		if (!handled)
 			break;
 
-		for (retry = 0; retry < 3; retry++) {
-			int wret;
-
-			wret = drm_dp_dpcd_write(&intel_dp->aux,
-						 DP_SINK_COUNT_ESI+1,
-						 &esi[1], 3);
-			if (wret == 3)
-				break;
-		}
+		if (!intel_dp_ack_sink_irq_esi(intel_dp, esi))
+			drm_dbg_kms(&i915->drm, "Failed to ack ESI\n");
 	}
 
 	return link_ok;