Public bug reported: I use a Dell Pro 13 Plus 2-in-1 to take notes using xournalpp. I noticed that, if I connect an external screen with the HDMI cable, the pen starts working intermittently and I can see a long list of messages in dmesg like the following:
[Fri Aug 14 13:48:42 2026] wacom 0018:056A:4A64.0001: wacom_wac_queue_insert: kfifo has filled, starting to drop events If I disconnect the HDMI cable, the pen starts working again as expected. I have also tried to connect the external screen through the usb-c port and an adapter (using the same HDMI cable and the same external screen), and the problem does not occur in this case. During these tests I have disconnected any other electronic devices (such as ear pods and external keyboard). I have also tried with and without the power adapter, and exactly the same issue occurs. Expected behavior: the pen should work the same way with and without the HDMI cable plugged in. Below I list information of my system according to the instructions > lsb_release -rd Description: Ubuntu 26.04 LTS Release: 26.04 > apt-cache policy libwacom-common libwacom-common: Installed: 2.18.0-1 Candidate: 2.18.0-1 Version table: *** 2.18.0-1 500 500 http://archive.ubuntu.com/ubuntu resolute/main amd64 Packages 500 http://archive.ubuntu.com/ubuntu resolute/main i386 Packages 100 /var/lib/dpkg/status > apt-cache policy libwacom9:amd64 libwacom9: Installed: 2.18.0-1 Candidate: 2.18.0-1 Version table: *** 2.18.0-1 500 500 http://archive.ubuntu.com/ubuntu resolute/main amd64 Packages 100 /var/lib/dpkg/status ** Affects: libwacom (Ubuntu) Importance: Undecided Status: New ** Description changed: I use a Dell Pro 13 Plus 2-in-1 to take notes using xournalpp. I noticed that, if I connect an external screen with the HDMI cable, the pen starts working intermittently and I can see a long list of messages in dmesg like the following: [Fri Aug 14 13:48:42 2026] wacom 0018:056A:4A64.0001: wacom_wac_queue_insert: kfifo has filled, starting to drop events If I disconnect the HDMI cable, the pen starts working again as - expected. I have also tried to connect the external cable through the + expected. I have also tried to connect the external screen through the usb-c port and an adapter (using the same HDMI cable and the same external screen), and the problem does not occur in this case. During these tests I have disconnected any other electronic devices (such as ear pods and external keyboard). I have also tried with and without the power adapter, and exactly the same issue occurs. Expected behavior: the pen should work the same way with and without the HDMI cable plugged in. Below I list information of my system according to the instructions > lsb_release -rd Description: Ubuntu 26.04 LTS Release: 26.04 > apt-cache policy libwacom-common libwacom-common: - Installed: 2.18.0-1 - Candidate: 2.18.0-1 - Version table: - *** 2.18.0-1 500 - 500 http://archive.ubuntu.com/ubuntu resolute/main amd64 Packages - 500 http://archive.ubuntu.com/ubuntu resolute/main i386 Packages - 100 /var/lib/dpkg/status + Installed: 2.18.0-1 + Candidate: 2.18.0-1 + Version table: + *** 2.18.0-1 500 + 500 http://archive.ubuntu.com/ubuntu resolute/main amd64 Packages + 500 http://archive.ubuntu.com/ubuntu resolute/main i386 Packages + 100 /var/lib/dpkg/status > apt-cache policy libwacom9:amd64 libwacom9: - Installed: 2.18.0-1 - Candidate: 2.18.0-1 - Version table: - *** 2.18.0-1 500 - 500 http://archive.ubuntu.com/ubuntu resolute/main amd64 Packages - 100 /var/lib/dpkg/status + Installed: 2.18.0-1 + Candidate: 2.18.0-1 + Version table: + *** 2.18.0-1 500 + 500 http://archive.ubuntu.com/ubuntu resolute/main amd64 Packages + 100 /var/lib/dpkg/status -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2163483 Title: Pen works intermittently when HDMI cable connected To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libwacom/+bug/2163483/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
