commit 9ed2312c678f41b7922fe74425ab589fe2ca287b
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Fri Oct 1 12:38:08 2010 -0700

    drm/i915/dp: wait for HPD bit to set before using main eDP link
    
    DP spec wants this, might help avoid some of the questionable delays in
    this code.
    
    Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ae4abf7..53917d7 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -764,9 +764,70 @@ intel_dp_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode,
 	}
 }
 
+/* Wait for HPD bit to set before trying to use AUX channel */
+static void ironlake_edp_clear_hpd(struct intel_dp *intel_dp)
+{
+	struct drm_device *dev = intel_dp->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t output_reg = intel_dp->output_reg;
+	uint32_t hpd_reg;
+	uint32_t hpd_mask;
+
+	switch (output_reg) {
+	case DP_A:
+		hpd_reg = DIGITAL_PORT_HOTPLUG_CNTRL;
+		hpd_mask = DIGITAL_PORTA_LONG_PULSE_DETECT_MASK |
+			DIGITAL_PORTA_SHORT_PULSE_DETECT_MASK;
+		break;
+	case PCH_DP_D:
+		hpd_reg = PCH_PORT_HOTPLUG;
+		hpd_mask = PORTD_HOTPLUG_LONG_DETECT |
+			PORTD_HOTPLUG_SHORT_DETECT;
+		break;
+	default:
+		DRM_ERROR("waiting for HPD on non-eDP panel\n");
+		return;
+	}
+
+	/* Ack any existing status */
+	I915_WRITE(hpd_reg, I915_READ(hpd_reg));
+}
+
+/* Wait for HPD bit to set before trying to use AUX channel */
+static void ironlake_edp_wait_hpd(struct intel_dp *intel_dp)
+{
+	struct drm_device *dev = intel_dp->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t output_reg = intel_dp->output_reg;
+	uint32_t hpd_reg;
+	uint32_t hpd_mask;
+
+	switch (output_reg) {
+	case DP_A:
+		hpd_reg = DIGITAL_PORT_HOTPLUG_CNTRL;
+		hpd_mask = DIGITAL_PORTA_LONG_PULSE_DETECT_MASK |
+			DIGITAL_PORTA_SHORT_PULSE_DETECT_MASK;
+		break;
+	case PCH_DP_D:
+		hpd_reg = PCH_PORT_HOTPLUG;
+		hpd_mask = PORTD_HOTPLUG_LONG_DETECT |
+			PORTD_HOTPLUG_SHORT_DETECT;
+		break;
+	default:
+		DRM_ERROR("waiting for HPD on non-eDP panel\n");
+		return;
+	}
+
+	if (wait_for(I915_READ(hpd_reg) & hpd_mask, 5000))
+		WARN(1, "panel HPD active wait timed out: 0x%08x\n",
+		     I915_READ(hpd_reg));
+	I915_WRITE(hpd_reg, I915_READ(hpd_reg));
+}
+
 /* Returns true if the panel was already on when called */
-static bool ironlake_edp_panel_on (struct drm_device *dev)
+static bool ironlake_edp_panel_on (struct intel_dp *intel_dp)
 {
+	struct drm_device *dev = intel_dp->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 pp;
 
@@ -788,10 +849,16 @@ static bool ironlake_edp_panel_on (struct drm_device *dev)
 	 */
 	msleep(300);
 
+	ironlake_edp_clear_hpd(intel_dp);
+
 	if (wait_for(I915_READ(PCH_PP_STATUS) & PP_ON, 5000))
 		DRM_ERROR("panel on wait timed out: 0x%08x\n",
 			  I915_READ(PCH_PP_STATUS));
 
+	/* If VDD was forced on, HPD will have already been set */
+	if (!(pp & EDP_FORCE_VDD))
+		ironlake_edp_wait_hpd(intel_dp);
+
 	pp &= ~(PANEL_UNLOCK_REGS);
 	pp |= PANEL_POWER_RESET; /* restore panel reset bit */
 	I915_WRITE(PCH_PP_CONTROL, pp);
@@ -830,16 +897,23 @@ static void ironlake_edp_panel_off (struct drm_device *dev)
 	msleep(300);
 }
 
-static void ironlake_edp_panel_vdd_on(struct drm_device *dev)
+static void ironlake_edp_panel_vdd_on(struct intel_dp *intel_dp)
 {
+	struct drm_device *dev = intel_dp->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 pp;
 
+	if (I915_READ(PCH_PP_CONTROL) & EDP_FORCE_VDD)
+		return;
+
+	ironlake_edp_clear_hpd(intel_dp);
+
 	pp = I915_READ(PCH_PP_CONTROL);
 	pp |= EDP_FORCE_VDD;
 	I915_WRITE(PCH_PP_CONTROL, pp);
 	POSTING_READ(PCH_PP_CONTROL);
-	msleep(300);
+
+	ironlake_edp_wait_hpd(intel_dp);
 }
 
 static void ironlake_edp_panel_vdd_off(struct drm_device *dev)
@@ -911,8 +985,11 @@ static void intel_dp_prepare(struct drm_encoder *encoder)
 	if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp)) {
 		ironlake_edp_panel_off(dev);
 		ironlake_edp_backlight_off(dev);
-		ironlake_edp_panel_vdd_on(dev);
-		ironlake_edp_pll_on(encoder);
+		ironlake_edp_panel_vdd_on(intel_dp);
+		if (!IS_PCH_eDP(intel_dp))
+			ironlake_edp_pll_on(encoder);
+		else
+			ironlake_edp_pll_off(encoder);
 	}
 	if (dp_reg & DP_PORT_EN)
 		intel_dp_link_down(intel_dp);
@@ -926,7 +1003,7 @@ static void intel_dp_commit(struct drm_encoder *encoder)
 	intel_dp_start_link_train(intel_dp);
 
 	if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp))
-		ironlake_edp_panel_on(dev);
+		ironlake_edp_panel_on(intel_dp);
 
 	intel_dp_complete_link_train(intel_dp);
 
@@ -955,7 +1032,7 @@ intel_dp_dpms(struct drm_encoder *encoder, int mode)
 		if (!(dp_reg & DP_PORT_EN)) {
 			intel_dp_start_link_train(intel_dp);
 			if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp))
-				ironlake_edp_panel_on(dev);
+				ironlake_edp_panel_on(intel_dp);
 			intel_dp_complete_link_train(intel_dp);
 			if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp))
 				ironlake_edp_backlight_on(dev);
@@ -1423,7 +1500,7 @@ ironlake_dp_detect(struct drm_connector *connector)
 
 	/* Panel needs power for AUX to work */
 	if (IS_eDP(intel_dp) || IS_PCH_eDP(intel_dp))
-		ironlake_edp_panel_vdd_on(connector->dev);
+		ironlake_edp_panel_vdd_on(intel_dp);
 	status = connector_status_disconnected;
 	if (intel_dp_aux_native_read(intel_dp,
 				     0x000, intel_dp->dpcd,