Hi, On Tue, May 24, 2022 at 01:55:23PM +0300, Heikki Krogerus wrote: > +Mika > > On Fri, May 20, 2022 at 12:22:50PM +0200, Stefan Hoffmeister wrote: > > I am trying to diagnose a problem where I get video output on > > Thunderbolt on one DisplayPort, but no output on the second > > DisplayPort. > > > > I would love to turn on all the (kernel-level) logging output that > > there is, but do not know how to do that. > > > > Basically, on a Dell Inspiron 16 Plus (7610) laptop with Thunderbolt > > 4, I am running Fedora Linux 36 with kernel 5.17+. > > > > Connecting that laptop to a Thunderbolt docking station (Intel > > Thunderbolt 3 chip inside), > > with two screens attached via DisplayPort, I get only one screen up and running. > > > > I'd like to discover more about this apparent error mode, because > > attaching a different TB3 > > setup works fine. I am looking for some means to enable logging or to > > get debugging insight. > > > > Generally speaking, I suspect that this specific Dell laptop > > (configuration) has some challenges > > in the BIOS, and with Thunderbolt in general, but am totally blind to > > what is going on. > > > > This system offers potential for fun, this being a hybrid PRIME > > configuration, with an Intel iGPU passing through to an Nvidia dGPU > > which seems to be the only wired-up way to get DisplayPort output. In that system all the tunneling is done by the firmware so there is really not much you can debug on the kernel side. You can add "thunderbolt.dyndbg" in the command line to get more verbose logging but I doubt it reveals anything useful. How do you connect the monitors to the dock and what dock it is?
