[PATCH v6 2/3] drm: Introduce epoch counter to drm_connector

[Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>]

This counter will be used by drm_helper_probe_detect caller to determine
if anything had changed(including edid, connection status and etc).
Hardware specific driver detect hooks are responsible for updating this
counter when some change is detected to notify the drm part,
which can trigger for example hotplug event.

Also now call drm_connector_update_edid_property
right after we get edid always to make sure there is a
unified way to handle edid change, without having to
change tons of source code as currently
drm_connector_update_edid_property is called only in
certain cases like reprobing and not right after edid is
actually updated.

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@intel.com>
---
 drivers/gpu/drm/drm_connector.c    | 16 +++++++++++++
 drivers/gpu/drm/drm_edid.c         |  3 +++
 drivers/gpu/drm/drm_probe_helper.c | 38 ++++++++++++++++++++++++++----
 include/drm/drm_connector.h        |  3 +++
 4 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 4c766624b20d..98fd236acc57 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 =
@@ -1866,6 +1867,7 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 	struct drm_device *dev = connector->dev;
 	size_t size = 0;
 	int ret;
+	const struct edid *old_edid;
 
 	/* ignore requests to set edid when overridden */
 	if (connector->override_edid)
@@ -1887,6 +1889,20 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 	else
 		drm_reset_display_info(connector);
 
+	if (connector->edid_blob_ptr) {
+		old_edid = (const struct edid *)connector->edid_blob_ptr->data;
+		if (old_edid) {
+			if (!drm_edid_are_equal(edid, old_edid)) {
+				DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Edid was changed.\n",
+				    connector->base.id, connector->name);
+
+				connector->epoch_counter += 1;
+				DRM_DEBUG_KMS("Updating change counter to %llu\n",
+				    connector->epoch_counter);
+			}
+		}
+	}
+
 	drm_object_property_set_value(&connector->base,
 				      dev->mode_config.non_desktop_property,
 				      connector->display_info.non_desktop);
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 0639db9fd23f..48b716abc9ef 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1803,6 +1803,9 @@ struct edid *drm_get_edid(struct drm_connector *connector,
 	edid = drm_do_get_edid(connector, drm_do_probe_ddc_edid, adapter);
 	if (edid)
 		drm_get_displayid(connector, edid);
+
+	drm_connector_update_edid_property(connector, edid);
+
 	return edid;
 }
 EXPORT_SYMBOL(drm_get_edid);
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 351cbc40f0f8..b2b6385cfed3 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -287,6 +287,9 @@ drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
 	if (WARN_ON(ret < 0))
 		ret = connector_status_unknown;
 
+	if (ret != connector->status)
+		connector->epoch_counter += 1;
+
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
 
@@ -320,11 +323,16 @@ drm_helper_probe_detect(struct drm_connector *connector,
 		return ret;
 
 	if (funcs->detect_ctx)
-		return funcs->detect_ctx(connector, ctx, force);
+		ret = funcs->detect_ctx(connector, ctx, force);
 	else if (connector->funcs->detect)
-		return connector->funcs->detect(connector, force);
+		ret = connector->funcs->detect(connector, force);
 	else
-		return connector_status_connected;
+		ret = connector_status_connected;
+
+	if (ret != connector->status)
+		connector->epoch_counter += 1;
+
+	return ret;
 }
 EXPORT_SYMBOL(drm_helper_probe_detect);
 
@@ -777,6 +785,7 @@ 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;
@@ -790,20 +799,39 @@ 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 epoch 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 epoch counter %llu\n",
+			      connector->base.id,
+			      connector->name,
+			      connector->epoch_counter);
+
+		/*
+		 * Check if epoch counter had changed, meaning that we need
+		 * to send a uevent.
+		 */
+		if (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 681cb590f952..a3cc7d0927d6 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1288,6 +1288,9 @@ 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

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