failed to detect external monitor via usb/3.0 (Ubuntu/20.04, intel/nvidia + DL-5910 chipset) when Xorg is used

[kngharv]

Dear all:

I am using a laptop in attempt to connect two monitors, which one of them I've decided that I want to connect via the Displaylink hub in attempt to lighten the load on my USB/3.0. My laptop has a intel AND a low-end nvidia GPU built in.

I installed displaylink driver using displaylink-debian without issue. Everything seems to work:

[Tue Sep 15 14:18:59 2020 <    1.196183>] evdi: [D] evdi_painter_connect:738 (dev=-1) Process is trying to connect
[Tue Sep 15 14:18:59 2020 <    0.000005>] evdi: [I] Task 15697 (DesktopManagerE) of process 15684 (DisplayLinkMana)
[Tue Sep 15 14:18:59 2020 <    0.000008>] evdi: [D] evdi_painter_connect:788 (dev=0) Connected with 000000002664e0aa
[Tue Sep 15 14:18:59 2020 <    0.000005>] evdi: [D] evdi_detect:90 (dev=0) poll connector state: connected
[Tue Sep 15 14:18:59 2020 <    0.084878>] evdi: [D] evdi_detect:94 (dev=0) poll connector state: disconnected
[Tue Sep 15 14:18:59 2020 <    0.000037>] evdi: [D] evdi_detect:94 (dev=0) poll connector state: disconnected
[Tue Sep 15 14:18:59 2020 <    0.000136>] evdi: [D] evdi_detect:94 (dev=0) poll connector state: disconnected
[Tue Sep 15 14:18:59 2020 <    0.000028>] evdi: [D] evdi_detect:94 (dev=0) poll connector state: disconnected
[Tue Sep 15 14:18:59 2020 <    0.000115>] evdi: [D] evdi_detect:94 (dev=0) poll connector state: disconnected
[Tue Sep 15 14:18:59 2020 <    0.000029>] evdi: [D] evdi_detect:94 (dev=0) poll connector state: disconnected
[Tue Sep 15 14:18:59 2020 <    0.000110>] evdi: [D] evdi_detect:90 (dev=0) poll connector state: connected
[Tue Sep 15 14:18:59 2020 <    0.000003>] evdi: [D] evdi_painter_get_edid_copy:228 (dev=0) EDID valid
[Tue Sep 15 14:18:59 2020 <    0.000134>] evdi: [D] evdi_detect:90 (dev=0) poll connector state: connected
[Tue Sep 15 14:18:59 2020 <    0.000003>] evdi: [D] evdi_painter_get_edid_copy:228 (dev=0) EDID valid

Output from xrandr --listproviders

$ xrandr --listproviders
Providers: number : 6
Provider 0: id: 0x44 cap: 0x0 crtcs: 3 outputs: 2 associated providers: 0 name:modesetting
Provider 1: id: 0x163 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 2: id: 0x141 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 3: id: 0x11f cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 4: id: 0xfd cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 5: id: 0xdb cap: 0x4, Source Offload crtcs: 0 outputs: 0 associated providers: 0 name:nouveau

Yet, the monitor attached to the usb/3.0 hub (Dell D3100 with Displaylink DL-5910 chipset) doesn't seems to work.

I almost want to say my the display via displaylink failed to detect, but upon close examination, SOMETHING managed to detect that 2 external monitors were detected (the monitor connected via displaylink is the card0-DVI-I-1 deice)

$ ls /sys/class/drm/*/status | xargs -I {} -i bash -c "echo -n {}: ; cat {}"
/sys/class/drm/card0-DVI-I-1/status:connected
/sys/class/drm/card1-DVI-I-2/status:disconnected
/sys/class/drm/card2-DVI-I-3/status:disconnected
/sys/class/drm/card3-DVI-I-4/status:disconnected
/sys/class/drm/card4-eDP-1/status:connected
/sys/class/drm/card4-HDMI-A-1/status:connected

On top of it, during the login process, gdm3 seems to detect the 2nd external monitor thus painted the background color to the 20.04 dark purple.

Once I log into gnome-shell, though, it seems that xrandr can't detect the 2nd external monitor. Here is the exerpt of xrandr -q.

$ xrandr -q|egrep -v ^\ 
Screen 0: minimum 320 x 200, current 3360 x 2560, maximum 16384 x 16384
eDP-1 connected primary 1920x1080+0+1103 (normal left inverted right x axis y axis) 344mm x 194mm
HDMI-1 connected 1440x2560+1920+0 left (normal left inverted right x axis y axis) 597mm x 336mm

In attempt to solve the problem, I manually edited 20-displaylink.conf file. The result is that there are a lot more error in dmesg:

[D] evdi_add_devices:156 Increasing device count to 4
[D] evdi_crtc_init:389 drm_crtc_init: 0 p0000000035f0a34a
[D] evdi_crtc_init:389 drm_crtc_init: 0 p000000008832db39
[D] evdi_crtc_init:389 drm_crtc_init: 0 p00000000c49f028e
[D] evdi_crtc_init:389 drm_crtc_init: 0 p00000000e2ca9527
[D] evdi_detect:90 (dev=0) poll connector state: connected
[D] evdi_detect:94 (dev=0) poll connector state: disconnected
[D] evdi_driver_postclose:133 (dev=0) Process tries to close us, postclose
[D] evdi_log_pixel_format:680 pixel format XR24 little-endian (0x34325258)
[D] evdi_painter_connect:738 (dev=0) Process is trying to connect
[D] evdi_painter_connect:788 (dev=0) Connected with 0000000032bf0dca
[D] evdi_painter_dpms_notify:654 (dev=0) Notifying dpms mode: 0
[D] evdi_painter_dpms_notify:654 (dev=0) Notifying dpms mode: 3
[D] evdi_painter_framebuffer_size:581 Scanout buffer not set.
[D] evdi_painter_get_edid_copy:228 (dev=0) EDID valid
[D] evdi_painter_mark_dirty:608 (dev=0) Skip clip rect. Scanout buffer not set.
[D] evdi_painter_mode_changed_notify:701 (dev=0) Notifying mode changed: 1280x1024@60; bpp 32; 
[I] Atomic driver:yes
[I] Initialising logging on level 5
[I] Task 1621 (gpu-manager) of process 1621 (gpu-manager)
[I] Task 1808 (DesktopManagerE) of process 1789 (DisplayLinkMana)
[I] Task 2340 (gnome-s:disk$0) of process 2217 (gnome-shell)
[I] Task 3700 (Xorg.wrap) of process 3700 (Xorg.wrap)
loading out-of-tree module taints kernel.
module verification failed: signature and/or required key missing - tainting kernel
[W] evdi_painter_send_event:307 Painter is not connected!
[W] evdi_painter_send_update_ready_if_needed:645 Painter does not exist!

Is there anything else I can try?

thanks in advance.

(The below is the displaylink-debian debug info)

--------------- Linux system info ----------------

Distro: Ubuntu
Release: focal
Kernel: 5.4.0-47-generic

---------------- DisplayLink info ----------------

Driver version: 1.7.0
DisplayLink service status: up and running
EVDI service version: 1.7.0

------------------ Graphics card -----------------

Vendor: i915
Subsystem: 530
VGA: Intel Corporation HD Graphics 530 (rev 06)
VGA (3D): NVIDIA Corporation GM107M [GeForce GTX 960M] (rev a2)
X11 version: 1.20.8-2ubuntu2.4
X11 configs: /etc/X11/xorg.conf /etc/X11/xorg.conf.d/20-displaylink.conf

-------------- DisplayLink xorg.conf -------------

File: /etc/X11/xorg.conf.d/20-displaylink.conf
Contents:
 Section "ServerLayout"
    Identifier "layout"
    Screen 0 "nvidia"
    Inactive "intel"
EndSection

Section "Device"
    Identifier "intel"
    Driver "modesetting"
    Option "AccelMethod" "None"
EndSection

Section "Screen"
    Identifier "intel"
    Device "intel"
EndSection


Section "Device"
    Identifier "nvidia"
##  manually changed from "nvidia" to "nouveau" b
    Driver "nouveau"
#    Option "ConstrainCursor" "off"
EndSection

Section "Screen"
    Identifier "nvidia"
    Device "nvidia"
    Option "AllowEmptyInitialConfiguration" "on"
    Option "IgnoreDisplayDevices" "CRT"
EndSection


## manually added per displaylink-debian troubleshooting page
Section "OutputClass"
    Identifier  "DisplayLink"
    MatchDriver "evdi"
    Driver      "modesetting"
    Option      "AccelMethod" "none"
EndSection

-------------------- Monitors --------------------

Providers: number : 6
Provider 0: id: 0x44 cap: 0x0 crtcs: 3 outputs: 2 associated providers: 0 name:modesetting
Provider 1: id: 0x163 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 2: id: 0x141 cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 3: id: 0x11f cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 4: id: 0xfd cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
Provider 5: id: 0xdb cap: 0x4, Source Offload crtcs: 0 outputs: 0 associated providers: 0 name:nouveau

[kngharv]

I never resolve the problem despite I have successfully installed the driver.

However, I kind of gotten around the problem by switching to Wayland instead of X11.

Wayland detected the monitor without issue.

Since I know nothing about Wayland, I am not sure why Wayland worked but X11 does not.

If anyone who managed to figure out how to get X11 to work, please let me know.

[kngharv]

solution found:
#469