Thinkpad T14 gen4
Fedora 40
After a recent upgrade to KDE Plasma 6.3 (early KDE Plasma 6.2), I am having trouble unlocking my computer using the fingerprint reader.
After locking the screen, unlocking with the fingerprint scanner only works for a few seconds. Earlier on KDE Plasma 6.2, after moving the mouse or pressing any key, it was possible to unlock the screen.
As I mentioned on KDE Plasma 6.3, this works only moments after locking the computer.
I noticed the same behavior (T14 Gen4 AMD, so I guess that should not be a a surprise). Unfortunately, I have no solution for this. I think we may have to wait a while for the Plasma team to fix this and other regressions.
In general, I have to say that the T14’s fingerprint reader is a noticeable step down from the one in the T16 I had before. When authentication fails, it immediately retries, without giving me time to reposition my finger. As a result, if I start with a less than ideal finger position, it often exhausts all tries in the span of a couple of seconds, then deativates the fingerprint reader, and I end up having to enter my password. The T16 had a noticeable wait period after a failed attempt, which allowed me to put my finger on the sensor properly.
I started to have problems with usb fingerprint scanner after 6.3 update as well. I have MSI laptop and the conditions are a bit different, but I’ve raised a bug for KDE: 500451 – Locker turns a fingerprint scanner on before system suspend
This may explain my issues with the fingerprint reader on my Thinkpad X13 Gen 2. I have only owned this device for a short time, so I wasn’t sure if it wasn’t a general problem with the hardware. I did a freh install of F41 before the 6.3 update. Fingerpint was working on login at that time. Now it only works a small fraction of the time. FP authentication is still working for elevating privileges (eg sudo).
Maybe it’s not a Thinkpad issue, it could be this bug here. Does this describe your problems?
Not really, but maybe the two problems are related.
Just want to add that I too have the same issue on my thinkpad t490 after updating to plasma 6.3.
Fingerprint login works for a few seconds immediately after locking the computer but if I’m gone for more I have to type the password.
The summary in this bug is something I have observed, too. In Plasma 6.3.x, after locking the screen, the password prompt is displayed immediately and the power LED next to my fingerprint scanner turns from white to green to indicate that it is ready and waiting for me to scan my finger. In Plasma 6.2.x, it would show the lockscreen wallpaper with the current time and only after I hit a key or clicked somewhere would it show my user picture, a password entry field, and fire up the fingerprint scanner.
This might actually be the root cause and the fingerprint scanner not working may well be just a side effect. IIRC, when libfprint is waiting for authentication, there is a timeout, maybe 20 or 30s. After that timeout, it turns the fingerprint reader off and requires a password. Maybe this is what happens here: I lock the system, it waits for authentication right away, and I can unlock with my fingerprint again. However, if I step away for a little longer or it locks automatically after some time, when I return the fingerprint scanner is not working. It is just a theory, but maybe this is because the scanner activates automatically when locking, reaches the timeout, and then is turned off and the system requires a password to unlock.
I created issue on KDE board: