UDL device cannot get its own screen

Böszörményi Zoltán zboszor at pr.hu
Wed Oct 23 12:12:03 UTC 2019

2019. 10. 23. 9:42 keltezéssel, Pekka Paalanen írta:
> On Tue, 22 Oct 2019 17:50:21 +0200
> Böszörményi Zoltán <zboszor at pr.hu> wrote:
>> Hi,
>> I have the below configuration for an Intel based POS system that,
>> while advertises 3 outputs (DP1, VGA1 and HDMI1 with xf86-video-intel),
>> only two are usable. DP1 for the built-in touchscreen and VGA1 for
>> the external VGA connector.
>> I wanted to use an USB DisplayLink device as the 3rd output, with all
>> three output using its own Screen number, i.e. :0.0 :0.1 and :0.2.
> ...
>> The third observation is that while I am using this configuration below,
>> so the UDL device should be assigned to :0.2 (and active!), it is really
>> assigned to :0[.0] as an inactive output. See that there's no "*" indicator
>> set for any of the supported modes on DVI-I-1-1.
>> How can I set up 3 different Screens correctly for 3 separate fullscreen
>> applications?
>> I am using Xorg 1.20.4 patched with the "autobind GPUs to the screen"
>> patch from Dave Airlie that at least wakes up the UDL device and makes
>> it visible without extra magic with providers/sinks.
> Hi,
> for your specific use case, auto-bind is exactly what you do not want.
> So drop the patch or (since the patch is in upstream master already)
> use the option it adds to stop auto-binding.

With Option "AutoBindGPU" "false" in effect (equivalent of backing the
patch out) the UDL device does not get assigned to ANY of the screens.

I want it to have its own :0.2 bit that doesn't happen.

> Thanks,
> pq

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