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

In commit cdb0e95bf571dccc1f75fef9bdad21b167ef0b37
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>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c63f54e..c14d407 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/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);