drm: Add HPD state to drm_connector_oob_hotplug_event()

In some implementations, such as the Qualcomm platforms, the display
driver has no way to query the current HPD state and as such it's
impossible to distinguish between disconnect and attention events.

Add a parameter to drm_connector_oob_hotplug_event() to pass the HPD
state.

Also push the test for unchanged state in the displayport altmode driver
into the i915 driver, to allow other drivers to act upon each update.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/gpu/drm/drm_connector.c

@@ -2825,6 +2825,7 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
 /**
  * drm_connector_oob_hotplug_event - Report out-of-band hotplug event to connector
  * @connector_fwnode: fwnode_handle to report the event on
+ * @hpd_state: hot plug detect logical state
  *
  * On some hardware a hotplug event notification may come from outside the display
  * driver / device. An example of this is some USB Type-C setups where the hardware
@@ -2834,7 +2835,8 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
  * This function can be used to report these out-of-band events after obtaining
  * a drm_connector reference through calling drm_connector_find_by_fwnode().
  */
-void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
+				     enum drm_connector_hpd_state hpd_state)
 {
 	struct drm_connector *connector;
 
@@ -2843,7 +2845,7 @@ void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
 		return;
 
 	if (connector->funcs->oob_hotplug_event)
-		connector->funcs->oob_hotplug_event(connector);
+		connector->funcs->oob_hotplug_event(connector, hpd_state);
 
 	drm_connector_put(connector);
 }

drivers/gpu/drm/i915/display/intel_dp.c

@@ -4825,15 +4825,26 @@ static int intel_dp_connector_atomic_check(struct drm_connector *conn,
 	return intel_modeset_synced_crtcs(state, conn);
 }
 
-static void intel_dp_oob_hotplug_event(struct drm_connector *connector)
+static void intel_dp_oob_hotplug_event(struct drm_connector *connector,
+				       enum drm_connector_hpd_state hpd_state)
 {
 	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
 	struct drm_i915_private *i915 = to_i915(connector->dev);
+	bool hpd_high = hpd_state == DRM_CONNECTOR_HPD_HIGH;
+	unsigned int hpd_pin = encoder->hpd_pin;
+	bool need_work = false;
 
 	spin_lock_irq(&i915->irq_lock);
-	i915->hotplug.event_bits |= BIT(encoder->hpd_pin);
+	if (hpd_high != test_bit(hpd_pin, &i915->hotplug.oob_hotplug_last_state, hpd_pin)) {
+		i915->hotplug.event_bits |= BIT(hpd_pin);
+
+		__assign_bit(hpd_pin, &i915->hotplug.oob_hotplug_last_state, hpg_high);
+		need_work = true;
+	}
 	spin_unlock_irq(&i915->irq_lock);
-	queue_delayed_work(system_wq, &i915->hotplug.hotplug_work, 0);
+
+	if (need_work)
+		queue_delayed_work(system_wq, &i915->hotplug.hotplug_work, 0);
 }
 
 static const struct drm_connector_funcs intel_dp_connector_funcs = {

drivers/gpu/drm/i915/i915_drv.h

@@ -138,6 +138,9 @@ struct i915_hotplug {
 	/* Whether or not to count short HPD IRQs in HPD storms */
 	u8 hpd_short_storm_enabled;
 
+	/* Last state reported by oob_hotplug_event for each encoder */
+	unsigned int oob_hotplug_last_state;
+
 	/*
 	 * if we get a HPD irq from DP and a HPD irq from non-DP
 	 * the non-DP HPD could block the workqueue on a mode config

drivers/usb/typec/altmodes/displayport.c

@@ -59,7 +59,6 @@ struct dp_altmode {
 	struct typec_displayport_data data;
 
 	enum dp_state state;
-	bool hpd;
 
 	struct mutex lock; /* device lock */
 	struct work_struct work;
@@ -143,10 +142,8 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
 		if (!ret)
 			dp->state = DP_STATE_CONFIGURE;
 	} else {
-		if (dp->hpd != hpd) {
-			drm_connector_oob_hotplug_event(dp->connector_fwnode);
-			dp->hpd = hpd;
-		}
+		drm_connector_oob_hotplug_event(dp->connector_fwnode,
+						hpd ? DRM_CONNECTOR_HPD_HIGH : DRM_CONNECTOR_HPD_LOW);
 	}
 
 	return ret;
@@ -573,8 +570,7 @@ void dp_altmode_remove(struct typec_altmode *alt)
 	cancel_work_sync(&dp->work);
 
 	if (dp->connector_fwnode) {
-		if (dp->hpd)
-			drm_connector_oob_hotplug_event(dp->connector_fwnode);
+		drm_connector_oob_hotplug_event(dp->connector_fwnode, DRM_CONNECTOR_HPD_LOW);
 
 		fwnode_handle_put(dp->connector_fwnode);
 	}

include/drm/drm_connector.h

@@ -142,6 +142,11 @@ enum subpixel_order {
 
 };
 
+enum drm_connector_hpd_state {
+	DRM_CONNECTOR_HPD_LOW,
+	DRM_CONNECTOR_HPD_HIGH
+};
+
 /**
  * struct drm_scrambling: sink's scrambling support.
  */
@@ -1141,7 +1146,8 @@ struct drm_connector_funcs {
 	 * This will get called when a hotplug-event for a drm-connector
 	 * has been received from a source outside the display driver / device.
 	 */
-	void (*oob_hotplug_event)(struct drm_connector *connector);
+	void (*oob_hotplug_event)(struct drm_connector *connector,
+				  enum drm_connector_hpd_state hpd_state);
 };
 
 /**
@@ -1742,7 +1748,8 @@ drm_connector_is_unregistered(struct drm_connector *connector)
 		DRM_CONNECTOR_UNREGISTERED;
 }
 
-void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode);
+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
+				     enum drm_connector_hpd_state hpd_state);
 const char *drm_get_connector_type_name(unsigned int connector_type);
 const char *drm_get_connector_status_name(enum drm_connector_status status);
 const char *drm_get_subpixel_order_name(enum subpixel_order order);