[Intel-gfx] [PATCH 14/17] drm/i915: Use hotplug callback to retrain DP link

[Keith Packard]

The display port link must be re-trained when
a monitor is plugged in.
---
 drivers/gpu/drm/i915/intel_dp.c |   21 ++++++++++++++++++---
 1 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ed3c7de..56b0119 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -538,6 +538,7 @@ intel_dp_dpms(struct drm_encoder *encoder, int mode)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t dp_reg = I915_READ(dp_priv->output_reg);
 
+	printk(KERN_ERR "DP dpms mode %d\n", mode);
 	if (mode != DRM_MODE_DPMS_ON) {
 		if (dp_reg & DP_PORT_EN)
 			intel_dp_link_down(intel_output, dp_priv->DP);
@@ -776,6 +777,7 @@ intel_dp_set_link_train(struct intel_output *intel_output,
 	struct intel_dp_priv *dp_priv = intel_output->dev_priv;
 	int ret;
 
+	printk(KERN_ERR "DP link train\n");
 	I915_WRITE(dp_priv->output_reg, dp_reg_value);
 	POSTING_READ(dp_priv->output_reg);
 	if (first)
@@ -904,6 +906,7 @@ intel_dp_link_down(struct intel_output *intel_output, uint32_t DP)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_dp_priv *dp_priv = intel_output->dev_priv;
 
+	printk(KERN_ERR "DP link down\n");
 	I915_WRITE(dp_priv->output_reg, DP & ~DP_PORT_EN);
 	POSTING_READ(dp_priv->output_reg);
 }
@@ -920,7 +923,6 @@ intel_dp_restore(struct drm_connector *connector)
 		intel_dp_link_down(intel_output,  dp_priv->save_DP);
 }
 
-#if 0
 /*
  * According to DP spec
  * 5.1.2:
@@ -940,14 +942,16 @@ intel_dp_check_link_status(struct intel_output *intel_output)
 		return;
 
 	if (!intel_dp_get_link_status(intel_output, link_status)) {
+		printk(KERN_ERR "DP link down, disabling DP output\n");
 		intel_dp_link_down(intel_output, dp_priv->DP);
 		return;
 	}
 
-	if (!intel_channel_eq_ok(link_status, dp_priv->lane_count))
+	if (!intel_channel_eq_ok(link_status, dp_priv->lane_count)) {
+		printk(KERN_ERR "DP link up, but link not stable. Training\n");
 		intel_dp_link_train(intel_output, dp_priv->DP, dp_priv->link_configuration);
+	}
 }
-#endif
 
 /**
  * Uses CRT_HOTPLUG_EN and CRT_HOTPLUG_STAT to detect DP connection.
@@ -1061,6 +1065,16 @@ static const struct drm_encoder_funcs intel_dp_enc_funcs = {
 };
 
 void
+intel_dp_hot_plug(struct intel_output *intel_output)
+{
+	struct intel_dp_priv *dp_priv = intel_output->dev_priv;
+
+	printk(KERN_ERR "intel_dp_hotplug\n");
+	if (dp_priv->dpms_mode == DRM_MODE_DPMS_ON)
+		intel_dp_check_link_status(intel_output);
+}
+
+void
 intel_dp_init(struct drm_device *dev, int output_reg)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -1103,6 +1117,7 @@ intel_dp_init(struct drm_device *dev, int output_reg)
 			  (output_reg == DP_B) ? "DPDDC-B" :
 			  (output_reg == DP_C) ? "DPDDC-C" : "DPDDC-D");
 	intel_output->ddc_bus = &dp_priv->adapter;
+	intel_output->hot_plug = intel_dp_hot_plug;
 
 	/* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
 	 * 0xd.  Failure to do so will result in spurious interrupts being
-- 
1.6.3.1