The bridge connector HPD handling path currently updates connector->status for every hpd_notify() invocation.
This does not work well for IRQ-only notifications where the event being reported is carried by extra_status and no connector status transition is associated with it. One example is DP MST. HPD IRQs are propagated through drm_bridge_hpd_notify_*() so that bridge drivers can process the notification. During MST operation, however, the SST connector attached to the bridge connector is intentionally kept disconnected while the MST topology manager handles all connector creation, removal and hotplug processing. Updating connector->status for an IRQ-only MST notification may cause the SST connector state to oscillate between connected and disconnected depending on the notification path. These artificial state transitions can later be detected by the polling logic and result in unnecessary hotplug events being generated. Userspace then re-probes connector status, potentially triggering the same sequence again. Treat notifications with status == connector_status_unknown and a valid extra_status as IRQ-only events. Forward the notification to bridge drivers without modifying connector->status. This keeps IRQ delivery working while leaving connector state management to the component that actually owns it, such as the DP MST topology framework. Signed-off-by: Yongxing Mou <[email protected]> --- drivers/gpu/drm/display/drm_bridge_connector.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c index 5edca47a025f..7334d6677604 100644 --- a/drivers/gpu/drm/display/drm_bridge_connector.c +++ b/drivers/gpu/drm/display/drm_bridge_connector.c @@ -163,6 +163,18 @@ static void drm_bridge_connector_handle_hpd(struct drm_bridge_connector *drm_bri struct drm_connector *connector = &drm_bridge_connector->base; struct drm_device *dev = connector->dev; + /* + * IRQ-only notification: extra_status carries the event but + * status is unknown — do not overwrite connector->status. + */ + if (status == connector_status_unknown && + extra_status != DRM_CONNECTOR_NO_EXTRA_STATUS) { + drm_bridge_connector_hpd_notify(connector, + connector->status, + extra_status, NULL); + return; + } + mutex_lock(&dev->mode_config.mutex); connector->status = status; mutex_unlock(&dev->mode_config.mutex); -- 2.43.0
