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#1 2022-11-10 19:07:50

Registered: 2022-11-10
Posts: 1

Dual 4K monitors with XPS 9360 and WD19TBS dock (maybe not possible)

I have a Dell XPS 9360 and am trying to drive two 4K monitors through a Dell WD19TBS docking station. The laptop supports HBR2 so according to the table here it should be capable of driving the two monitors at 60Hz, in principle. I'm connecting one monitor to the docking station's Thunderbolt port and one to HDMI, as listed in the table.

However, there is a footnote there that says that linux is "unable to physically turn off built-in display" and therefore only two QHD monitors can be supported (since the built-in display is FHD). Sure enough, when I try it one of the monitors is blank unless I use a lower resolution.

I did actually manage to disable the built-in screen by passing video=eDP-1:d to the kernel at startup. Having done that, xrandr shows the monitor as "disconnected" as does /sys/class/drm/card0-eDP-1/status. The two external monitors, DP-1 and DP-2 still show as "connected" in both places.

This all seemed rather promising. Maybe the statement in the manual isn't correct, or the situation has improved in the 5 years since that manual was published.

Unfortunately, when I do this only one of the external monitors actually works. During boot, the built in display goes blank as expected, but the tty only shows on one monitor. The other remains blank. In X, whatever I do with xrandr, despite the second monitor showing as connected I can't get any response out of it at any resolution / refresh rate.

Perhaps, as the manual says, it truly isn't possible to do this, but that will require me to buy a new laptop so I thought I'd see if anyone here has any ideas.

Last edited by grumpy_programmer (2022-11-10 21:04:14)


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