Kernels 5.4.51, 5.6.19, 5.7.9 tested and they do NOT exhibit this problem. Two kernels 5.8rc1 and 5.8rc5 show the problem. I assume other kernels in the range are affected and possibly will later kernels that will come after rc5. https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8-rc1/ https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8-rc5/ These are ubuntu compiled/build kernels of pristine upstream kernel.org sources (unpatched by debian or ubuntu). How to reproduce: 1) Use kde/plasma on kubuntu 20.04 (LTS) 2) Procure Samsung galaxy buds. 3) Install the affected kernels above and reboot. 4) Go to bluetooth widget on the panel on the and try to connect to Galaxy Buds (F7CB) Hard reset needed. Computer/plasma freezes and even soft reboot (CTRL+ALT+F1,CTRL+ALT+DEL) is not possible.
My laptop is HP Spectre x360 model 13-ae053na
Created attachment 290325 [details] bluetooth widget in plasma
For completeness. 1) I could connect to my phone Galaxy A50 5G via bluetooth before trying to connect to Earbuds. (see attached pic) 2) Bluetooth Widget in plasma shows Ear buds connected, but system is frozen anyway. 3) I can move cursor with touchpad, but it does not react to clicks after attempted connect. The only way to get out of this situation is to restart laptop.
I am not sure it is pure kernel problem. It looks like compatibility of combination of new kernel with system. There might be multiple of the small bugs that manifest themselves in the new kernel only. It works well in kernels 5.7 and earlier. 1) Connecting to Galaxy A90 5G via bluetooth from laptop does not work properly in one step from laptop and it never worked in one step from Laptop (even for older kernels.) Connection must be initiated from the phone or when initiated from laptop it still must be finalized/initiated from the phone as well. Otherwise widget keeps trying to connect, that might contribute to freezing. 2) After connecting to Galaxy earbuds , the bluetooth widget tries also to initiate connection to the phone Galaxy A90 5G automatically (why?). But the connection to the phone must be finalized at the phone end (why?). Trying to finalize connection from the phone freezes the laptop (only when laptop connection inititation is automatic.) Note that when I manually initiate connection to the phone Galaxy A90 5G from Laptop then I can finalize/initiate connection at the phone end without problem to establish connection. All devices (phone Galaxy A90 5G, and Galaxy ear buds) are assumed to be paired with Laptop already. It is possible the bug is in the audio part of the connection.
Please provide pre-compiled kernel binaries x86_64 leading up to 5.8rc1 and I will try to bisect or narrow down the problem or to find a commit causing this problem.
Same with Huawei Maimang 5 Something broke in between 5.7.12, and 5.8-r1
Just tested 5.8. Problem is still there.