diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_dp_link_training.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_dp_link_training.c | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c index 4da6e33c7fa1..a9f40985a621 100644 --- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -129,7 +129,8 @@ static bool intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) { uint8_t voltage; - int voltage_tries, max_vswing_tries; + int voltage_tries, cr_tries, max_cr_tries; + bool max_vswing_reached = false; uint8_t link_config[2]; uint8_t link_bw, rate_select; @@ -170,9 +171,21 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) return false; } + /* + * The DP 1.4 spec defines the max clock recovery retries value + * as 10 but for pre-DP 1.4 devices we set a very tolerant + * retry limit of 80 (4 voltage levels x 4 preemphasis levels x + * x 5 identical voltage retries). Since the previous specs didn't + * define a limit and created the possibility of an infinite loop + * we want to prevent any sync from triggering that corner case. + */ + if (intel_dp->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14) + max_cr_tries = 10; + else + max_cr_tries = 80; + voltage_tries = 1; - max_vswing_tries = 0; - for (;;) { + for (cr_tries = 0; cr_tries < max_cr_tries; ++cr_tries) { uint8_t link_status[DP_LINK_STATUS_SIZE]; drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd); @@ -192,7 +205,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) return false; } - if (max_vswing_tries == 1) { + if (max_vswing_reached) { DRM_DEBUG_KMS("Max Voltage Swing reached\n"); return false; } @@ -213,9 +226,11 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) voltage_tries = 1; if (intel_dp_link_max_vswing_reached(intel_dp)) - ++max_vswing_tries; + max_vswing_reached = true; } + DRM_ERROR("Failed clock recovery %d times, giving up!\n", max_cr_tries); + return false; } /* |