[PATCH 2/2] drm/i915: Associate ACPI connector nodes with connector entries

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

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).

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 40 ++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 008560ef4db0..27aea2ef80ac 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -15526,6 +15526,45 @@ static int intel_initial_commit(struct drm_device *dev)
 	return ret;
 }
 
+/* NOTE: The connector order must be final before this is called. */
+static void intel_assign_connector_fwnodes(struct drm_device *dev)
+{
+	struct drm_connector_list_iter conn_iter;
+	struct device *kdev = &dev->pdev->dev;
+	struct fwnode_handle *fwnode = NULL;
+	struct drm_connector *connector;
+	struct acpi_device *adev;
+
+	drm_connector_list_iter_begin(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(kdev, 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(kdev),
+						      0x1f, 0);
+			if (adev) {
+				connector->fwnode = acpi_fwnode_handle(adev);
+				break;
+			}
+			/* fallthrough */
+		default:
+			connector->fwnode = fwnode;
+			break;
+		}
+	}
+	drm_connector_list_iter_end(&conn_iter);
+}
+
 int intel_modeset_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
@@ -15630,6 +15669,7 @@ int intel_modeset_init(struct drm_device *dev)
 
 	drm_modeset_lock_all(dev);
 	intel_modeset_setup_hw_state(dev, dev->mode_config.acquire_ctx);
+	intel_assign_connector_fwnodes(dev);
 	drm_modeset_unlock_all(dev);
 
 	for_each_intel_crtc(dev, crtc) {
-- 
2.20.1