[Intel-gfx] [PATCH] drm/i915: Splitting intel_dp_check_link_status

[Shubhangi Shrivastava]

When created originally intel_dp_check_link_status()
was supposed to handle only link training for short
pulse but has grown into handler for short pulse itself.
This patch cleans up this function by splitting it into
two halves. First intel_dp_short_pulse() is called,
which will be entry point and handle all logic for
short pulse handling while intel_dp_check_link_status()
will retain its original purpose of only doing link
status related work.
The link retraining part when EQ is not correct is
retained to intel_dp_check_link_status whereas other
operations are handled as part of intel_dp_short_pulse.
This change is required to avoid performing all DPCD
related operations on performing link retraining.

v2: Added WARN_ON to intel_dp_check_link_status()
    Removed a call to intel_dp_get_link_status() (Ander)

Tested-by: Nathan D Ciobanu <nathan.d.ciobanu at intel.com>
Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani at intel.com>
Signed-off-by: Shubhangi Shrivastava <shubhangi.shrivastava at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 65 +++++++++++++++++++++++------------------
 1 file changed, 36 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 82ee18d..f8d9611 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4279,6 +4279,36 @@ go_again:
 	return -EINVAL;
 }
 
+static void
+intel_dp_check_link_status(struct intel_dp *intel_dp)
+{
+	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
+	struct drm_device *dev = intel_dp_to_dev(intel_dp);
+	u8 link_status[DP_LINK_STATUS_SIZE];
+
+	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;
+	}
+
+	if (!intel_encoder->base.crtc)
+		return;
+
+	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
+		return;
+
+	/* 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:
@@ -4288,14 +4318,10 @@ go_again:
  *  4. Check link status on receipt of hot-plug interrupt
  */
 static void
-intel_dp_check_link_status(struct intel_dp *intel_dp)
+intel_dp_short_pulse(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
-	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
 	u8 sink_irq_vector;
-	u8 link_status[DP_LINK_STATUS_SIZE];
-
-	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
 	/*
 	 * Clearing compliance test variables to allow capturing
@@ -4305,17 +4331,6 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 	intel_dp->compliance_test_type = 0;
 	intel_dp->compliance_test_data = 0;
 
-	if (!intel_encoder->base.crtc)
-		return;
-
-	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
-		return;
-
-	/* Try to read receiver status if the link appears to be up */
-	if (!intel_dp_get_link_status(intel_dp, link_status)) {
-		return;
-	}
-
 	/* Now read the DPCD to see if it's actually running */
 	if (!intel_dp_get_dpcd(intel_dp)) {
 		return;
@@ -4335,14 +4350,9 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 			DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
 	}
 
-	/* 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);
-	}
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+	intel_dp_check_link_status(intel_dp);
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
 }
 
 /* XXX this is probably wrong for multiple downstream ports */
@@ -5072,11 +5082,8 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 			}
 		}
 
-		if (!intel_dp->is_mst) {
-			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
-			intel_dp_check_link_status(intel_dp);
-			drm_modeset_unlock(&dev->mode_config.connection_mutex);
-		}
+		if (!intel_dp->is_mst)
+			intel_dp_short_pulse(intel_dp);
 	}
 
 	ret = IRQ_HANDLED;
-- 
2.6.1