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>

1 files changed, 5 insertions, 10 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c63f54e84847..c14d407d41e8 100644
--- 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);