drm/i915: Associate ACPI connector nodes with connector entries (v2)

On Intel platforms we know that the ACPI connector device
node order will follow the order the driver (i915) decides.
The decision is made using the custom Intel ACPI OpRegion
(intel_opregion.c), though the driver does not actually know
that the values it sends to ACPI there are used for
associating a device node for the connectors, and assigning
address for them.

In reality that custom Intel ACPI OpRegion actually violates
ACPI specification (we supply dynamic information to objects
that are defined static, for example _ADR), however, it
makes assigning correct connector node for a connector entry
straightforward (it's one-on-one mapping).

Changes in v2 (Hans de goede):
- Take a reference on the fwnode which we assign to the connector,
  for ACPI nodes this is a no-op but in the future we may see
  software-fwnodes assigned to connectors which are ref-counted.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210817215201.795062-6-hdegoede@redhat.com

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

@@ -282,3 +282,49 @@ void intel_acpi_device_id_update(struct drm_i915_private *dev_priv)
 	}
 	drm_connector_list_iter_end(&conn_iter);
 }
+
+/* NOTE: The connector order must be final before this is called. */
+void intel_acpi_assign_connector_fwnodes(struct drm_i915_private *i915)
+{
+	struct drm_connector_list_iter conn_iter;
+	struct drm_device *drm_dev = &i915->drm;
+	struct fwnode_handle *fwnode = NULL;
+	struct drm_connector *connector;
+	struct acpi_device *adev;
+
+	drm_connector_list_iter_begin(drm_dev, &conn_iter);
+	drm_for_each_connector_iter(connector, &conn_iter) {
+		/* Always getting the next, even when the last was not used. */
+		fwnode = device_get_next_child_node(drm_dev->dev, fwnode);
+		if (!fwnode)
+			break;
+
+		switch (connector->connector_type) {
+		case DRM_MODE_CONNECTOR_LVDS:
+		case DRM_MODE_CONNECTOR_eDP:
+		case DRM_MODE_CONNECTOR_DSI:
+			/*
+			 * Integrated displays have a specific address 0x1f on
+			 * most Intel platforms, but not on all of them.
+			 */
+			adev = acpi_find_child_device(ACPI_COMPANION(drm_dev->dev),
+						      0x1f, 0);
+			if (adev) {
+				connector->fwnode =
+					fwnode_handle_get(acpi_fwnode_handle(adev));
+				break;
+			}
+			fallthrough;
+		default:
+			connector->fwnode = fwnode_handle_get(fwnode);
+			break;
+		}
+	}
+	drm_connector_list_iter_end(&conn_iter);
+	/*
+	 * device_get_next_child_node() takes a reference on the fwnode, if
+	 * we stopped iterating because we are out of connectors we need to
+	 * put this, otherwise fwnode is NULL and the put is a no-op.
+	 */
+	fwnode_handle_put(fwnode);
+}

drivers/gpu/drm/i915/display/intel_acpi.h

@@ -13,6 +13,7 @@ void intel_register_dsm_handler(void);
 void intel_unregister_dsm_handler(void);
 void intel_dsm_get_bios_data_funcs_supported(struct drm_i915_private *i915);
 void intel_acpi_device_id_update(struct drm_i915_private *i915);
+void intel_acpi_assign_connector_fwnodes(struct drm_i915_private *i915);
 #else
 static inline void intel_register_dsm_handler(void) { return; }
 static inline void intel_unregister_dsm_handler(void) { return; }
@@ -20,6 +21,8 @@ static inline
 void intel_dsm_get_bios_data_funcs_supported(struct drm_i915_private *i915) { return; }
 static inline
 void intel_acpi_device_id_update(struct drm_i915_private *i915) { return; }
+static inline
+void intel_acpi_assign_connector_fwnodes(struct drm_i915_private *i915) { return; }
 #endif /* CONFIG_ACPI */
 
 #endif /* __INTEL_ACPI_H__ */

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

@@ -11670,6 +11670,7 @@ int intel_modeset_init_nogem(struct drm_i915_private *i915)
 
 	drm_modeset_lock_all(dev);
 	intel_modeset_setup_hw_state(dev, dev->mode_config.acquire_ctx);
+	intel_acpi_assign_connector_fwnodes(i915);
 	drm_modeset_unlock_all(dev);
 
 	for_each_intel_crtc(dev, crtc) {