[Intel-gfx] [PATCH] drm/i915: intel_dp_check_link_status should only return status of link

[Manasi Navare]

Intel_dp_check_link_status() function reads the Link status registers
and returns a boolean to indicate link is good or bad.
If the link is bad, it is retrained outside the function based
on the return value.

Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 6d586b7..c795c9e 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3863,7 +3863,7 @@ go_again:
 	return -EINVAL;
 }
 
-static void
+static bool
 intel_dp_check_link_status(struct intel_dp *intel_dp)
 {
 	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
@@ -3873,26 +3873,25 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
 	if (!intel_dp_get_link_status(intel_dp, link_status)) {
-		DRM_ERROR("Failed to get link status\n");
-		return;
+		DRM_DEBUG_KMS("Failed to get link status\n");
+		return false;
 	}
 
-	if (!intel_encoder->base.crtc)
-		return;
+	/* Check if the link is valid by reading the bits of Link status
+	 * registers
+	 */
+	if (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count) ||
+	    !drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
+		DRM_DEBUG_KMS("Channel EQ or CR not ok, need to retrain\n");
+		return false;
+	}
 
-	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
-		return;
+	DRM_DEBUG_KMS("Link is good, no need to retrain\n");
+	return true;
 
-	/* if link training is requested we should perform it always */
-	if ((intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) ||
-	    (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count))) {
-		DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
-			      intel_encoder->base.name);
-		intel_dp_start_link_train(intel_dp);
-		intel_dp_stop_link_train(intel_dp);
-	}
 }
 
+
 /*
  * According to DP spec
  * 5.1.2:
@@ -3950,7 +3949,11 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
 	}
 
 	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
-	intel_dp_check_link_status(intel_dp);
+	if (!intel_dp_check_link_status(intel_dp) ||
+	    intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) {
+		intel_dp_start_link_train(intel_dp);
+		intel_dp_stop_link_train(intel_dp);
+	}
 	drm_modeset_unlock(&dev->mode_config.connection_mutex);
 
 	return true;
@@ -4271,7 +4274,11 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
 		 * link loss triggerring long pulse!!!!
 		 */
 		drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
-		intel_dp_check_link_status(intel_dp);
+		if (!intel_dp_check_link_status(intel_dp) ||
+		    intel_dp->compliance_test_type == DP_TEST_LINK_TRAINING) {
+			intel_dp_start_link_train(intel_dp);
+			intel_dp_stop_link_train(intel_dp);
+		}
 		drm_modeset_unlock(&dev->mode_config.connection_mutex);
 		goto out;
 	}
-- 
1.9.1