I have 3 DisplayLink USB3 adapters connected to my PC (yes, it's a notebook so I can't use any PCIe graphics cards). Every adapter has 2 output ports (1x HDMI, 1x DVI). These adapters are i-tec U3DUALADA, but I think it doesn't matter because the problem will be somewhere in the X environment.
System: Debian Buster, Xfce
When I connect 6 monitors to these adapters, the system acts like this:
- first 4 connected monitors are working, other 2 don't
- no mather in which ports these are connected in
In the DisplayLink log file, I see DisplayLink knows about all of the connected monitors (when I disconnect/connect any monitor, DisplayLink adds some output to the log file).
But there are two strange things in xrandr:
1/ When I start connecting DisplayLink adapters, xrandr --listproviders outputs:
After 1st connected adapter:
root@fix-x270:/etc/X11# xrandr --listproviders
Providers: number : 3
Provider 0: id: 0x4a cap: 0xf, Source Output, Sink Output, Source
Offload, Sink Offload crtcs: 3 outputs: 8 associated providers: 0 name:modesetting
Provider 1: id: 0x283 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 2: id: 0x261 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
After 2nd connected adapter:
root@fix-x270:/etc/X11# xrandr --listproviders
Providers: number : 5
Provider 0: id: 0x4a cap: 0xf, Source Output, Sink Output, Source
Offload, Sink Offload crtcs: 3 outputs: 8 associated providers: 0 name:modesetting
Provider 1: id: 0x283 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 2: id: 0x261 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 3: id: 0x23e cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 4: id: 0x21c cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
After 3rd connected adapter:
root@fix-x270:/etc/X11# xrandr --listproviders
Providers: number : 6
Provider 0: id: 0x4a cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 3 outputs: 8 associated providers: 0 name:modesetting
Provider 1: id: 0x283 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 2: id: 0x261 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 3: id: 0x23e cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 4: id: 0x21c cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 5: id: 0x1f5 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
As you can see, Provider 6 is missing, which is the first problem.
2/ When I use these providers by:
xrandr --setprovideroutputsource 1 0
xrandr --setprovideroutputsource 2 0
xrandr --setprovideroutputsource 3 0
xrandr --setprovideroutputsource 4 0
xrandr --setprovideroutputsource 5 0
When I would run xrandr --setprovideroutputsource 6 0, ofcourse it says Could not find provider with index 6.
When I run ls /sys/class/drm/*/status | xargs -I {} -i bash -c "echo -n {}: ; cat {}", it outputs:
/sys/class/drm/card0-DP-1/status:disconnected
/sys/class/drm/card0-DP-2/status:disconnected
/sys/class/drm/card0-DP-3/status:disconnected
/sys/class/drm/card0-DP-4/status:connected
/sys/class/drm/card0-DP-5/status:connected
/sys/class/drm/card0-eDP-1/status:connected
/sys/class/drm/card0-HDMI-A-1/status:disconnected
/sys/class/drm/card0-HDMI-A-2/status:disconnected
/sys/class/drm/card1-DVI-I-1/status:connected
/sys/class/drm/card2-DVI-I-2/status:connected
/sys/class/drm/card3-DVI-I-3/status:connected
/sys/class/drm/card4-DVI-I-4/status:connected
/sys/class/drm/card5-DVI-I-5/status:disconnected
First three monitors are connected directly to the PC, they are not interesting for us, because they work as they should.
Strange thing is that card5-DVI-I-5 is always disconnected, which is the second problem.
9 monitor setup is something not as common, so I was unable to find any similar problem.
Thank you for your advice.
fix
