[Dell Inspiron 3531] "Unknown" display found in display utility [8086:0f31]

[Po-Hsu Lin]

CID: 201403-14892 Inspiron 3531

Even without external monitor connected, there is an "unknown" display in the display utility.
And in the screenshot, you can see the extended desktop.

ubuntu@201403-14892:~$ xrandr -q
Screen 0: minimum 320 x 200, current 2390 x 768, maximum 32767 x 32767
eDP1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1366x768 60.0*+ 39.9
   1360x768 59.8 60.0
   1024x768 60.0
   800x600 60.3 56.2
   640x480 59.9
VGA1 connected 1024x768+1366+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768 60.0*
   800x600 60.3 56.2
   848x480 60.0
   640x480 59.9
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

ubuntu@201403-14892:~$ lspci -nn| grep '\[03'
00:02.0 VGA compatible controller [0300]: Intel Corporation Atom Processor Z36xxx/Z37xxx Series Graphics & Display [8086:0f31] (rev 0e)

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-39-generic 3.13.0-39.66
ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu 1520 F.... pulseaudio
CRDA:
 country TW:
  (2402 - 2472 @ 40), (3, 27)
  (5270 - 5330 @ 40), (3, 17), DFS
  (5735 - 5815 @ 40), (3, 30)
CurrentDesktop: Unity
Date: Mon Nov 17 23:02:14 2014
HibernationDevice: RESUME=UUID=217ae5ce-6101-4b1d-8ed3-e5df8cacfafa
InstallationDate: Installed on 2014-11-17 (0 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
Lsusb:
 Bus 001 Device 005: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
 Bus 001 Device 004: ID 1a40:0101 Terminus Technology Inc. Hub
 Bus 001 Device 003: ID 0c45:64ad Microdia
 Bus 001 Device 002: ID 8087:07e6 Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. Inspiron 3531
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-39-generic root=UUID=34aa7766-e502-48af-81d4-5a155b69c395 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-39-generic N/A
 linux-backports-modules-3.13.0-39-generic N/A
 linux-firmware 1.127.8
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
StagingDrivers: rts5139
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/02/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A02_UpdateMCU
dmi.board.name: 00FTTX
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A02_UpdateMCU
dmi.modalias: dmi:bvnDellInc.:bvrA02_UpdateMCU:bd07/02/2014:svnDellInc.:pnInspiron3531:pvrA02_UpdateMCU:rvnDellInc.:rn00FTTX:rvrA00:cvnDellInc.:ct8:cvrA02_UpdateMCU:
dmi.product.name: Inspiron 3531
dmi.product.version: A02_UpdateMCU
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Po-Hsu Lin (cypressyew)]

A workaround to get rid of this "Unknown" display is to change:
GRUB_CMDLINE_LINUX=""
into:
GRUB_CMDLINE_LINUX="video=VGA-1:d"
(Since the bogus unknown display is connected to VGA1)

Run "sudo update-grub" and reboot

Reference:
http://askubuntu.com/questions/398903/unknown-display-besides-laptop-built-in-display-old-question-but-with-no-answer

Also note that there is only a HDMI port on this system.

[Po-Hsu Lin (cypressyew)]

Confirmed with Ara, this should be considered as a blocker.

[Po-Hsu Lin (cypressyew)]

Verified on 201403-14892
This issue does not exist in 3.5.0-54, 3.8.0-44

No display on 3.11 / 3.12 kernel, unable to test
Error message could be found in dmesg:
[ 42.575835] [drm:intel_dp_complete_link_train] *ERROR* failed to train DP, aborting
(can't even switch to console, but I can ssh to it)
3.13.0-39, this issue exists.

[Po-Hsu Lin (cypressyew)]

Also affect 201404-14984 Dell Inspiron 3531, another Bay-Trail system (with the same video controller, [8086:0f31])

[Anthony Wong (anthonywong)]

@Po-Hsu
Could you try drm-intel-nightly kernel at http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/current/ ?
If that still does not work, I will report this issue to upstream.

[Timo Aaltonen (tjaalton)]

also test the current sru kernel available from trusty-updates, it switched baytrail to use i915_bdw driver

[Po-Hsu Lin (cypressyew)]

Hi Anthony,
I have verified with the drm-intel-nightly kernel (version 4.0.0-994) on 201403-14892, and it could get rid of the unknown display.
Thanks

[Taihsiang Ho (tai271828)]

Dell Inspiron 3147 - Redwood (CID 201403-14889)
with 14.04.2 fresh installation

with the same video chipset
00:02.0 VGA compatible controller [0300]: Intel Corporation Atom Processor Z36xxx/Z37xxx Series Graphics & Display [8086:0f31] (rev 0e)

could NOT reproduce this issue.

screenshot inside the attachment 201403-14889-lp1393651.tar.gz

[Po-Hsu Lin (cypressyew)]

Unable to reproduce this on 3.16 kernel with 201403-14891, a desktop system with 14.04.2 stock image.

ubuntu@201403-14891:~$ uname -a
Linux 201403-14891 3.16.0-30-generic #40~14.04.1-Ubuntu SMP Thu Jan 15 17:43:14 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
ubuntu@201403-14891:~$ lspci -nn | grep '\[03'
00:02.0 VGA compatible controller [0300]: Intel Corporation Atom Processor Z36xxx/Z37xxx Series Graphics & Display [8086:0f31] (rev 0c)