drm/i915/bxt: Fix PPS lost state after suspend breaking eDP link training

The PPS registers are backed by power well #0 and as such may be reset
after system or runtime suspend (both implying a possible DC9
transition). Fix this by reusing the VLV/CHV PPS pipe-reassignment
logic. The difference on BXT is that the PPS instances are not pipe but
port (or more accurately pin) specific, so we only need to care about
the lost HW state. As opposed to VLV/CHV the SW state is fixed and
initialized during connector init.

This also paves the way towards using the actual port->PPS instance
mapping based on VBT.

This fixes eDP link training errors on BXT after suspend, where we
started the link training too early due to an incorrect T3 (panel power
on) register value.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96436Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466084243-5388-2-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -426,6 +426,37 @@ vlv_power_sequencer_pipe(struct intel_dp *intel_dp)
 	return intel_dp->pps_pipe;
 }
 
+static int
+bxt_power_sequencer_idx(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct drm_device *dev = intel_dig_port->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	lockdep_assert_held(&dev_priv->pps_mutex);
+
+	/* We should never land here with regular DP ports */
+	WARN_ON(!is_edp(intel_dp));
+
+	/*
+	 * TODO: BXT has 2 PPS instances. The correct port->PPS instance
+	 * mapping needs to be retrieved from VBT, for now just hard-code to
+	 * use instance #0 always.
+	 */
+	if (!intel_dp->pps_reset)
+		return 0;
+
+	intel_dp->pps_reset = false;
+
+	/*
+	 * Only the HW needs to be reprogrammed, the SW state is fixed and
+	 * has been setup during connector init.
+	 */
+	intel_dp_init_panel_power_sequencer_registers(dev, intel_dp);
+
+	return 0;
+}
+
 typedef bool (*vlv_pipe_check)(struct drm_i915_private *dev_priv,
 			       enum pipe pipe);
 
@@ -507,12 +538,13 @@ vlv_initial_power_sequencer_setup(struct intel_dp *intel_dp)
 	intel_dp_init_panel_power_sequencer_registers(dev, intel_dp);
 }
 
-void vlv_power_sequencer_reset(struct drm_i915_private *dev_priv)
+void intel_power_sequencer_reset(struct drm_i915_private *dev_priv)
 {
 	struct drm_device *dev = dev_priv->dev;
 	struct intel_encoder *encoder;
 
-	if (WARN_ON(!IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev)))
+	if (WARN_ON(!IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev) &&
+		    !IS_BROXTON(dev)))
 		return;
 
 	/*
@@ -532,7 +564,10 @@ void vlv_power_sequencer_reset(struct drm_i915_private *dev_priv)
 			continue;
 
 		intel_dp = enc_to_intel_dp(&encoder->base);
-		intel_dp->pps_pipe = INVALID_PIPE;
+		if (IS_BROXTON(dev))
+			intel_dp->pps_reset = true;
+		else
+			intel_dp->pps_pipe = INVALID_PIPE;
 	}
 }
 
@@ -542,7 +577,7 @@ _pp_ctrl_reg(struct intel_dp *intel_dp)
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 
 	if (IS_BROXTON(dev))
-		return BXT_PP_CONTROL(0);
+		return BXT_PP_CONTROL(bxt_power_sequencer_idx(intel_dp));
 	else if (HAS_PCH_SPLIT(dev))
 		return PCH_PP_CONTROL;
 	else
@@ -555,7 +590,7 @@ _pp_stat_reg(struct intel_dp *intel_dp)
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 
 	if (IS_BROXTON(dev))
-		return BXT_PP_STATUS(0);
+		return BXT_PP_STATUS(bxt_power_sequencer_idx(intel_dp));
 	else if (HAS_PCH_SPLIT(dev))
 		return PCH_PP_STATUS;
 	else
@@ -4719,14 +4754,11 @@ intel_dp_init_panel_power_sequencer(struct drm_device *dev,
 		return;
 
 	if (IS_BROXTON(dev)) {
-		/*
-		 * TODO: BXT has 2 sets of PPS registers.
-		 * Correct Register for Broxton need to be identified
-		 * using VBT. hardcoding for now
-		 */
-		pp_ctrl_reg = BXT_PP_CONTROL(0);
-		pp_on_reg = BXT_PP_ON_DELAYS(0);
-		pp_off_reg = BXT_PP_OFF_DELAYS(0);
+		int idx = bxt_power_sequencer_idx(intel_dp);
+
+		pp_ctrl_reg = BXT_PP_CONTROL(idx);
+		pp_on_reg = BXT_PP_ON_DELAYS(idx);
+		pp_off_reg = BXT_PP_OFF_DELAYS(idx);
 	} else if (HAS_PCH_SPLIT(dev)) {
 		pp_ctrl_reg = PCH_PP_CONTROL;
 		pp_on_reg = PCH_PP_ON_DELAYS;
@@ -4839,14 +4871,11 @@ intel_dp_init_panel_power_sequencer_registers(struct drm_device *dev,
 	lockdep_assert_held(&dev_priv->pps_mutex);
 
 	if (IS_BROXTON(dev)) {
-		/*
-		 * TODO: BXT has 2 sets of PPS registers.
-		 * Correct Register for Broxton need to be identified
-		 * using VBT. hardcoding for now
-		 */
-		pp_ctrl_reg = BXT_PP_CONTROL(0);
-		pp_on_reg = BXT_PP_ON_DELAYS(0);
-		pp_off_reg = BXT_PP_OFF_DELAYS(0);
+		int idx = bxt_power_sequencer_idx(intel_dp);
+
+		pp_ctrl_reg = BXT_PP_CONTROL(idx);
+		pp_on_reg = BXT_PP_ON_DELAYS(idx);
+		pp_off_reg = BXT_PP_OFF_DELAYS(idx);
 
 	} else if (HAS_PCH_SPLIT(dev)) {
 		pp_on_reg = PCH_PP_ON_DELAYS;

drivers/gpu/drm/i915/intel_drv.h

@@ -870,6 +870,11 @@ struct intel_dp {
 	 * this port. Only relevant on VLV/CHV.
 	 */
 	enum pipe pps_pipe;
+	/*
+	 * Set if the sequencer may be reset due to a power transition,
+	 * requiring a reinitialization. Only relevant on BXT.
+	 */
+	bool pps_reset;
 	struct edp_power_seq pps_delays;
 
 	bool can_mst; /* this port supports mst */
@@ -1347,7 +1352,7 @@ void intel_dp_mst_resume(struct drm_device *dev);
 int intel_dp_max_link_rate(struct intel_dp *intel_dp);
 int intel_dp_rate_select(struct intel_dp *intel_dp, int rate);
 void intel_dp_hot_plug(struct intel_encoder *intel_encoder);
-void vlv_power_sequencer_reset(struct drm_i915_private *dev_priv);
+void intel_power_sequencer_reset(struct drm_i915_private *dev_priv);
 uint32_t intel_dp_pack_aux(const uint8_t *src, int src_bytes);
 void intel_plane_destroy(struct drm_plane *plane);
 void intel_edp_drrs_enable(struct intel_dp *intel_dp);

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -578,6 +578,7 @@ void bxt_enable_dc9(struct drm_i915_private *dev_priv)
 
 	DRM_DEBUG_KMS("Enabling DC9\n");
 
+	intel_power_sequencer_reset(dev_priv);
 	gen9_set_dc_state(dev_priv, DC_STATE_EN_DC9);
 }
 
@@ -1112,7 +1113,7 @@ static void vlv_display_power_well_deinit(struct drm_i915_private *dev_priv)
 	/* make sure we're done processing display irqs */
 	synchronize_irq(dev_priv->dev->irq);
 
-	vlv_power_sequencer_reset(dev_priv);
+	intel_power_sequencer_reset(dev_priv);
 }
 
 static void vlv_display_power_well_enable(struct drm_i915_private *dev_priv,