modeset: Loss of VGA signal (ast2500) on login

[Chris Sheppard]

I am creating a new computer platforms. It provides two video sources: an Intel i915 DisplayPort and an AST2500 VGA. The i915 also provides HDMI, but it is disconnected/disabled.

EXPECTED BEHAVIOR: Video is presented through the AST2500 to VGA and the i915 to DisplayPort, mergine the displays to a unified layout when a layout is provided to xorg.

ACTUAL BEHAVIOR: Both monitors present a purple background at login, but the VGA monitor is quickly disabled at login.

When I had a problem with these video sources under Windows the Intel team provided me a "Switchable Graphics" BIOS module. It resolved the issue there. My BIOS settings define "Switchable Graphics" as the Primary Display.

When I set the BIOS to use the ast2500 as the only display source the system works as intended. I mention this to confirm the ast2500 and kernel can display video even if the ast2500 won't display video alongside the i915.

Description: Ubuntu 18.04.4 LTS
Release: 18.04

xorg:
  Installed: 1:7.7+19ubuntu7.1
  Candidate: 1:7.7+19ubuntu7.1
  Version table:
 *** 1:7.7+19ubuntu7.1 500
        500 http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:7.7+19ubuntu7 500
        500 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

test@test:~$ modinfo ast | grep -version
filename: /lib/modules/5.3.0-46-generic/kernel/drivers/gpu/drm/ast/ast.ko
license: GPL and additional rights
description: AST
author: Dave Airlie
firmware: ast_dp501_fw.bin
alias: pci:v00001A03d00002010sv*sd*bc03sc*i*
alias: pci:v00001A03d00002000sv*sd*bc03sc*i*
depends: drm,drm_kms_helper,drm_vram_helper,i2c-algo-bit
retpoline: Y
intree: Y
name: ast
vermagic: 5.3.0-46-generic SMP mod_unload
signat: PKCS#7
signer:
sig_key:
sig_hashalgo: md4
parm: modeset:Disable/Enable modesetting (int)

test@test:~$ xrandr --listproviders
Providers: number : 2
Provider 0: id: 0x6e cap: 0x9, Source Output, Sink Offload crtcs: 3 outputs: 2 associated providers: 0 name:modesetting
Provider 1: id: 0x41 cap: 0x0 crtcs: 1 outputs: 1 associated providers: 0 name:modesetting

Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
DP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 496mm x 292mm
   1920x1080 60.00*+
   1680x1050 59.95
   1600x900 60.00
   1280x1024 60.02
   1440x900 59.89
   1280x800 59.81
   1280x720 60.00
   1024x768 60.00
   800x600 60.32
   640x480 59.94
   720x400 70.08
HDMI-1 disconnected (normal left inverted right x axis y axis)

test@test:~$ sudo lshw -C video
[sudo] password for test:
  *-display
       description: VGA compatible controller
       product: Intel Corporation
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 02
       width: 64 bits
       clock: 33MHz
       capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:152 memory:90000000-90ffffff memory:80000000-8fffffff ioport:6000(size=64) memory:c0000-dffff
  *-display
       description: VGA compatible controller
       product: ASPEED Graphics Family
       vendor: ASPEED Technology, Inc.
       physical id: 0
       bus info: pci@0000:04:00.0
       version: 41
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi vga_controller cap_list
       configuration: driver=ast latency=0
       resources: irq:18 memory:91000000-91ffffff memory:92000000-9201ffff ioport:4000(size=128)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7.1
ProcVersionSignature: Ubuntu 5.3.0-46.38~18.04.1-generic 5.3.18
Uname: Linux 5.3.0-46-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.14
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 7 09:02:34 2020
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
 Intel Corporation Device [8086:3e9a] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Intel Corporation Device [8086:2212]
 ASPEED Technology, Inc. ASPEED Graphics Family [1a03:2000] (rev 41) (prog-if 00 [VGA controller])
   Subsystem: ASPEED Technology, Inc. ASPEED Graphics Family [1a03:2000]
InstallationDate: Installed on 2020-04-06 (0 days ago)
InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
MachineType: Trenton Systems Inc. MXT8287 0000000000
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-46-generic root=UUID=a9905566-7697-44d9-b626-03d5dd8fa6be ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/11/2019
dmi.bios.vendor: INSYDE Corp.
dmi.bios.version: 05.23.04.0041
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: MXT8287
dmi.board.vendor: Trenton Systems Inc.
dmi.board.version: Type2 - Board Version
dmi.chassis.asset.tag: Chassis Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Chassis Manufacturer
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnINSYDECorp.:bvr05.23.04.0041:bd06/11/2019:svnTrentonSystemsInc.:pnMXT82870000000000:pvr00000000000000000000:rvnTrentonSystemsInc.:rnMXT8287:rvrType2-BoardVersion:cvnChassisManufacturer:ct10:cvrChassisVersion:
dmi.product.family: Type1Family
dmi.product.name: MXT8287 0000000000
dmi.product.sku: Type1Sku0
dmi.product.version: 00000000000000000000
dmi.sys.vendor: Trenton Systems Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.99-1ubuntu1~18.04.2
version.libgl1-mesa-dri: libgl1-mesa-dri 19.2.8-0ubuntu0~18.04.3
version.libgl1-mesa-glx: libgl1-mesa-glx 19.2.8-0ubuntu0~18.04.3
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

[Daniel van Vugt (vanvugt)]

The attached Xorg log files seem to show that it knows about both GPUs and it claims to be using both...

1. Are you able to work around the problem by logging into "Ubuntu on Wayland" instead?

2. Does the same problem also occur in Ubuntu 20.04 (to be released soon)? http://cdimage.ubuntu.com/daily-live/current/ or in 19.10 (https://ubuntu.com/download/desktop)?

[Chris Sheppard (trenton-cls)]

Ubuntu 18.04 using Wayland: The monitor connected to the AST2500 VGA has no signal during and after login. "xrandr -q" shows both devices are active. They are listed as XWAYLAND0 and XWAYLAND1. Ubuntu desktop's "Display configuration" window shows both monitors are active. I can move the monitors relative to each other and change the monitor assigned as "primary". When I change these configurations the only thing that appears to be amiss is the missing AST2500 VGA video signal.

Ubuntu 20.04 using xorg: The monitor connected to the AST2500 VGA has no signal during or after login. "xrandr -q" shows the DisplayPort and HDMI that are part of the i915 (this machine does not provide the HDMI part of the i915); it does not show the AST2500 device. lspci and lshw show the AST2500 is present. Ubuntu desktop's "Display configuration" window only has options for one monitor.

Ubuntu 20.04 using Wayland: I seem to recall switching Ubuntu 20.04 from xorg to wayland using a button in the lower right corner of the login menu to present a menu that permitted me to toggle between xorg and wayland. The button only appears while I am entering the password at the login screen. Today that same button presents a different menu. The options are "Remmina kiosk" and "Ubuntu". I do not know how to toggle to Wayland without the button and I don't recall well enough to recount what I saw in Wayland earlier this week.

I will look into Ubuntu 19 tomorrow.

[Daniel van Vugt (vanvugt)]

Oh, actually this might be a mutter bug or even a kernel bug related to this:

https://gitlab.gnome.org/GNOME/mutter/-/issues/182

[Chris Sheppard (trenton-cls)]

I get the same behavior and many of the same syslog messages when I boot to XUbuntu, which does not rely on mutter. I am still investigating the kernel bug you referred me to. Thanks.

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.

Ubuntu 18.04 (bionic) reached end-of-standard-support on May 31, 2023.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it anymore. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in.