[PATCH v3 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.

v2: Added documentation for the new counter. Rename change_counter to
    epoch_counter.

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        |  3 +++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index d49e19f3de3a..9c5e63b31527 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -246,6 +246,7 @@ int drm_connector_init(struct drm_device *dev,
 	INIT_LIST_HEAD(&connector->modes);
 	mutex_init(&connector->mutex);
 	connector->edid_blob_ptr = NULL;
+	connector->epoch_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..5857053174da 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_epoch_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_epoch_counter = connector->epoch_counter;
+
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Old change counter %llu\n", connector->base.id,
+			      connector->name,
+			      old_epoch_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->epoch_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_epoch_counter != connector->epoch_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 fc5d08438333..58b24d44de9c 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1282,6 +1282,9 @@ struct drm_connector {
 	/** @override_edid: has the EDID been overwritten through debugfs for testing? */
 	bool override_edid;
 
+	/** @epoch_counter: used to detect any other changes in connector, besides status */
+	uint64_t epoch_counter;
+
 #define DRM_CONNECTOR_MAX_ENCODER 3
 	/**
 	 * @encoder_ids: Valid encoders for this connector. Please only use
-- 
2.17.1