From: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
This function cleans up clock recovery loop in link training compliant
tp Dp Spec 1.2. It tries the clock recovery 5 times for the same voltage
or until max voltage swing is reached and removes the additional non
compliant retries. This function now returns a boolean values based on
if clock recovery passed or failed.
v3:
* Better Debug prints in case of failures (Mika Kahola)
v2:
* Rebased on top of new revision of vswing patch (Manasi Navare)
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp_link_training.c | 60 +++++++++++++--------------
1 file changed, 28 insertions(+), 32 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
index b9880cf..80b9326 100644
--- a/drivers/gpu/drm/i915/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
@@ -125,12 +125,11 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp)
}
/* Enable corresponding port and start training pattern 1 */
-static void
+static bool
intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
{
- int i;
uint8_t voltage;
- int voltage_tries, loop_tries;
+ int voltage_tries, max_vswing_tries;
uint8_t link_config[2];
uint8_t link_bw, rate_select;
@@ -146,6 +145,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
+
if (intel_dp->num_sink_rates)
drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
&rate_select, 1);
@@ -161,58 +161,54 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
DP_TRAINING_PATTERN_1 |
DP_LINK_SCRAMBLING_DISABLE)) {
DRM_ERROR("failed to enable link training\n");
- return;
+ return false;
}
- voltage = 0xff;
- voltage_tries = 0;
- loop_tries = 0;
+ voltage_tries = 1;
+ max_vswing_tries = 0;
for (;;) {
uint8_t link_status[DP_LINK_STATUS_SIZE];
drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
+
if (!intel_dp_get_link_status(intel_dp, link_status)) {
DRM_ERROR("failed to get link status\n");
- break;
+ return false;
}
if (drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
DRM_DEBUG_KMS("clock recovery OK\n");
- break;
+ return true;
}
- /* Check to see if we've tried the max voltage */
- if (intel_dp_link_max_vswing_reached(intel_dp)) {
- ++loop_tries;
- if (loop_tries == 5) {
- DRM_ERROR("too many full retries, give up\n");
- intel_dp_dump_link_status(link_status);
- break;
- }
- intel_dp_reset_link_train(intel_dp,
- DP_TRAINING_PATTERN_1 |
- DP_LINK_SCRAMBLING_DISABLE);
- voltage_tries = 0;
- continue;
+ if (voltage_tries == 5) {
+ DRM_DEBUG_KMS("Same voltage tried 5 times\n");
+ return false;
+ }
+
+ if (max_vswing_tries == 1) {
+ DRM_DEBUG_KMS("Max Voltage Swing reached\n");
+ return false;
}
- /* 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_ERROR("too many voltage retries, give up\n");
- break;
- }
- } else
- voltage_tries = 0;
voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
/* Update training set as requested by target */
intel_get_adjust_train(intel_dp, link_status);
if (!intel_dp_update_link_train(intel_dp)) {
DRM_ERROR("failed to update link training\n");
- break;
+ return false;
}
+
+ if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) ==
+ voltage)
+ ++voltage_tries;
+ else
+ voltage_tries = 1;
+
+ if (intel_dp_link_max_vswing_reached(intel_dp))
+ ++max_vswing_tries;
+
}
}
--
1.9.1
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