On Mon, May 30, 2022 at 10:33 AM Tomasz Moń <desowin@xxxxxxxxx> wrote: > > On Sun, 2022-05-29 at 21:51 +0200, Stefan Hoffmeister wrote: > > I have managed to wedge the system into a state where it does not > > know about Thunderbolt, and now, on what I presume to be USB-C only > Could you please tell how did you wedge the system into a state where > it does not know about Thunderbolt? I was thinking of going the "find a bad-enough good cable" route as mentioned by Mika, but then I discovered that I possess only * a Thunderbolt cable * a 100W power delivery cable (which to my surprise still does what appears to be USB 2.0) and that it was the weekend. Incidentally I had been poking at the "Dell Client Configuration Toolkit" (hardly advertised) previously - which, at least in its RedHat 8 incarnation, will destroy anything related to openssl (in particular sudoers) through ldconfig on Fedora 36 in a native installation, with much fun ensuing given a disabled root account. But I digress. The "Dell Client Configuration Toolkit" gives you command-line access to the BIOS on modern (2018+) Dell boxes; this exposes a BIOS configuration option (not visible / recognizable in the BIOS UI) to set "ThunderboltPorts" to "Disabled". Setting that to "Enabled" didn't make the laptop explode, so "Disabled" apparently reconfigured / forced the onboard TB4 Intel controller to forget everything about Thunderbolt, ending up with plain USB-C at revision 1.2 (pretty old). Net observable effect: "only the first screen works on Thunderbolt" we go to * Windows 11 can do "2.5K@60 Hz + 4K @ 30 Hz", and * Linux can do a slightly _flakey_"2.5K + 4K @ 60 Hz". I like a stable 60 Hz screen refresh rate (enabled by native Thunderbolt bandwidth)
