drm/i915: Try harder to complete DP training pattern 1

In commit cdb0e95
Author: Keith Packard <keithp@keithp.com>
Date:   Tue Nov 1 20:00:06 2011 -0700

    drm/i915: Try harder during dp pattern 1 link training

extra passes were made to retry the same voltage and then retry a full
clock reset. However, as coverity pointed out, we never tried the full
clock reset as we broke out of the loop early.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -1798,8 +1798,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 			if ((intel_dp->train_set[i] & DP_TRAIN_MAX_SWING_REACHED) == 0)
 				break;
 		if (i == intel_dp->lane_count && voltage_tries == 5) {
-			++loop_tries;
-			if (loop_tries == 5) {
+			if (++loop_tries == 5) {
 				DRM_DEBUG_KMS("too many full retries, give up\n");
 				break;
 			}
@@ -1809,15 +1808,11 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 		}
 
 		/* Check to see if we've tried the same voltage 5 times */
-		if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) == voltage) {
-			++voltage_tries;
-			if (voltage_tries == 5) {
-				DRM_DEBUG_KMS("too many voltage retries, give up\n");
-				break;
-			}
-		} else
+		if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) != voltage) {
+			voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
 			voltage_tries = 0;
-		voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
+		} else
+			++voltage_tries;
 
 		/* Compute new intel_dp->train_set as requested by target */
 		intel_get_adjust_train(intel_dp, link_status);