drm/i915/bxt: WA for swapped HPD pins in A stepping

WA for BXT A0/A1, where DDIB's HPD pin is swapped to DDIA, so enabling
DDIA HPD pin in place of DDIB.

v2: For DP, irq_port is used to determine the encoder instead of
hpd_pin and removing the edp HPD logic because port A HPD is not
present(Imre)
v3: Rebased on top of Imre's patchset for enabling HPD on PORT A.
Added hpd_pin swapping for intel_dp_init_connector, setting encoder
for PORT_A as per the WA in irq_port (Imre)
v4: Dont enable interrupt for edp, also reframe the description (Siva)
v5: Don’t check for PORT_A in intel_ddi_init to update dig_port,
instead avoid setting hpd_pin itself (Imre)
Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -3243,7 +3243,15 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
 			goto err;
 
 		intel_dig_port->hpd_pulse = intel_dp_hpd_pulse;
-		dev_priv->hotplug.irq_port[port] = intel_dig_port;
+		/*
+		 * On BXT A0/A1, sw needs to activate DDIA HPD logic and
+		 * interrupts to check the external panel connection.
+		 */
+		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) < BXT_REVID_B0)
+					 && port == PORT_B)
+			dev_priv->hotplug.irq_port[PORT_A] = intel_dig_port;
+		else
+			dev_priv->hotplug.irq_port[port] = intel_dig_port;
 	}
 
 	/* In theory we don't need the encoder->type check, but leave it just in

drivers/gpu/drm/i915/intel_dp.c

@@ -5876,6 +5876,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 		break;
 	case PORT_B:
 		intel_encoder->hpd_pin = HPD_PORT_B;
+		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) < BXT_REVID_B0))
+			intel_encoder->hpd_pin = HPD_PORT_A;
 		break;
 	case PORT_C:
 		intel_encoder->hpd_pin = HPD_PORT_C;

drivers/gpu/drm/i915/intel_hdmi.c

@@ -1973,7 +1973,14 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 			intel_hdmi->ddc_bus = GMBUS_PIN_1_BXT;
 		else
 			intel_hdmi->ddc_bus = GMBUS_PIN_DPB;
-		intel_encoder->hpd_pin = HPD_PORT_B;
+		/*
+		 * On BXT A0/A1, sw needs to activate DDIA HPD logic and
+		 * interrupts to check the external panel connection.
+		 */
+		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) < BXT_REVID_B0))
+			intel_encoder->hpd_pin = HPD_PORT_A;
+		else
+			intel_encoder->hpd_pin = HPD_PORT_B;
 		break;
 	case PORT_C:
 		if (IS_BROXTON(dev_priv))