[PATCH v1 2/3] drm: Introduce change counter to drm_connector

[Stanislav Lisovskiy]

This counter will be used by drm_helper_probe_detect caller to determine
if something else had changed except connection status,
like for example edid. Hardware specific drivers are responsible
for updating this counter when some change is detected to notify
the drm part, which can trigger for example hotplug event.

Currently there is no way to propagate that to a calling layer,
as we send only connection_status update, however as we see with
edid the changes can be broader.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105540
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/drm_connector.c    |  1 +
 drivers/gpu/drm/drm_probe_helper.c | 29 +++++++++++++++++++++++++++--
 include/drm/drm_connector.h        |  2 ++
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 3ccdcf3dfcde..531983707d7f 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -245,6 +245,7 @@ int drm_connector_init(struct drm_device *dev,
 	INIT_LIST_HEAD(&connector->modes);
 	mutex_init(&connector->mutex);
 	connector->edid_blob_ptr = NULL;
+	connector->change_counter = 0;
 	connector->tile_blob_ptr = NULL;
 	connector->status = connector_status_unknown;
 	connector->display_info.panel_orientation =
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index ef2c468205a2..e8f41fa336c3 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -776,6 +776,7 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
 	struct drm_connector_list_iter conn_iter;
 	enum drm_connector_status old_status;
 	bool changed = false;
+	uint64_t old_change_counter;
 
 	if (!dev->mode_config.poll_enabled)
 		return false;
@@ -789,20 +790,44 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
 
 		old_status = connector->status;
 
+		old_change_counter = connector->change_counter;
+
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Old change counter %llu\n", connector->base.id,
+			      connector->name,
+			      old_change_counter);
+
 		connector->status = drm_helper_probe_detect(connector, NULL, false);
 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
 			      connector->base.id,
 			      connector->name,
 			      drm_get_connector_status_name(old_status),
 			      drm_get_connector_status_name(connector->status));
-		if (old_status != connector->status)
+
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] New change counter %llu\n",
+			      connector->base.id,
+			      connector->name,
+			      connector->change_counter);
+
+		if (old_status != connector->status) {
 			changed = true;
+		}
+
+		/* Check changing of edid when a connector status still remains
+		 * as "connector_status_connected".
+		 */
+		if (connector->status == connector_status_connected &&
+		    old_status == connector_status_connected &&
+		    old_change_counter != connector->change_counter) {
+			changed = true;
+		}
 	}
 	drm_connector_list_iter_end(&conn_iter);
 	mutex_unlock(&dev->mode_config.mutex);
 
-	if (changed)
+	if (changed) {
 		drm_kms_helper_hotplug_event(dev);
+		DRM_DEBUG_KMS("Sent hotplug event\n");
+	}
 
 	return changed;
 }
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index c6f8486d8b8f..feaa4eb673f6 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1155,6 +1155,8 @@ struct drm_connector {
 	/** @override_edid: has the EDID been overwritten through debugfs for testing? */
 	bool override_edid;
 
+	uint64_t change_counter;
+
 #define DRM_CONNECTOR_MAX_ENCODER 3
 	/**
 	 * @encoder_ids: Valid encoders for this connector. Please only use
-- 
2.17.1