On 3/24/25 06:24, Johan Hovold wrote:
The PMIC GLINK driver is currently generating DisplayPort hotplug notifications whenever something is connected to (or disconnected from) a port regardless of the type of notification sent by the firmware.
These notifications are forwarded to user space by the DRM subsystem as connector "change" uevents:
KERNEL[1556.223776] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) ACTION=change DEVPATH=/devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 SUBSYSTEM=drm HOTPLUG=1 CONNECTOR=36 DEVNAME=/dev/dri/card0 DEVTYPE=drm_minor SEQNUM=4176 MAJOR=226 MINOR=0On the Lenovo ThinkPad X13s and T14s, the PMIC GLINK firmware sends two identical notifications with orientation information when connecting a charger, each generating a bogus DRM hotplug event. On the X13s, two such notification are also sent every 90 seconds while a charger remains connected, which again are forwarded to user space:
port = 1, svid = ff00, mode = 255, hpd_state = 0 payload = 01 00 00 00 00 00 00 ff 00 00 00 00 00 00 00 00Note that the firmware only sends on of these when connecting an ethernet adapter.
Fix the spurious hotplug events by only forwarding hotplug notifications for the Type-C DisplayPort service id. This also reduces the number of uevents from four to two when an actual DisplayPort altmode device is connected:
port = 0, svid = ff01, mode = 2, hpd_state = 0 payload = 00 01 02 00 f2 0c 01 ff 03 00 00 00 00 00 00 00 port = 0, svid = ff01, mode = 2, hpd_state = 1 payload = 00 01 02 00 f2 0c 01 ff 43 00 00 00 00 00 00 00Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support") Cc: stable@vger.kernel.org # 6.3 Cc: Bjorn Andersson andersson@kernel.org Reported-by: Clayton Craft clayton@craftyguy.net Signed-off-by: Johan Hovold johan+linaro@kernel.org
Clayton reported seeing display flickering with recent RC kernels, which may possibly be related to these spurious events being generated with even greater frequency.
That still remains to be fully understood, but the spurious events, that on the X13s are generated every 90 seconds, should be fixed either way.
When a display/dock (which has ethernet) is connected, I see this hotplug change event 2 times (every 30 seconds) which I think you said this is expected now?
UDEV [236.150574] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [236.588696] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [266.208175] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [266.644710] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [296.243187] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [296.678177] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [326.276256] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm) UDEV [326.712248] change /devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0 (drm)
Not sure about you seeing it every 90s vs my 30s... anyways, I no longer see these events when a PD charger is connected though, so this patch seems to help with that!
Tested-by: Clayton Craft clayton@craftyguy.net