[i915] WARN_ON(!encoder->crtc), more warnings and unstable X on 16.04

[Luiz Angelo Daros de Luca]

Hello,

I installed ubuntu 16.04 on the vintage asus eeepc 701.
However, i915 is giving me warnings on dmesg and it is unstable, specially on vt-switch (I cannot go back to X).

I'll attach what dmesg shows me.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-28.47-generic 4.4.13
Uname: Linux 4.4.0-28-generic i686
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.1
Architecture: i386
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Wed Jul 6 00:52:20 2016
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller [8086:2592] (rev 04) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Mobile 915GM/GMS/910GML Express Graphics Controller [1043:82d9]
   Subsystem: ASUSTeK Computer Inc. Mobile 915GM/GMS/910GML Express Graphics Controller [1043:82d9]
MachineType: ASUSTeK Computer INC. 701
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.4.0-28-generic root=UUID=88e47f5f-2717-42af-a83c-05a041cf9895 ro rootflags=subvol=@ quiet splash forcepae vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/03/2008
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0910
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: 701
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: x.xx
dmi.chassis.asset.tag: 0x00000000
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTek Computer INC.
dmi.chassis.version: x.x
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0910:bd03/03/2008:svnASUSTeKComputerINC.:pn701:pvrx.x:rvnASUSTeKComputerINC.:rn701:rvrx.xx:cvnASUSTekComputerINC.:ct10:cvrx.x:
dmi.product.name: 701
dmi.product.version: x.x
dmi.sys.vendor: ASUSTeK Computer INC.
version.compiz: compiz 1:0.9.12.2+16.04.20160526-0ubuntu1
version.libdrm2: libdrm2 2.4.67-1ubuntu0.16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.2.0-1ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.2.0-1ubuntu2
version.xserver-xorg-core: xserver-xorg-core 2:1.18.3-1ubuntu2.2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.1-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2
xserver.bootTime: Wed Jul 6 00:20:43 2016
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.18.3-1ubuntu2.2

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Riccardo Battistini (rickb)]

The bug shows up in these Dell Latitude models
D430 i915GM
D630 iGM965
D610 i915GM
D530 iGM965

Ubuntu 14.04 both standard and with Xenial backports is also affected.

Regards
Riccardo

[dan (johntrialpro)]

can confirm this on my pc
Host bridge: 915GM/PM/GMS/910GML / pentium M 1.7 lubuntu 14.04.5 i386

ive with tested the following kernels
3.19.0-80 is ok
4.2.0-22 is ok
4.2.0-42 is ok

4.4.0-21 many errors
4.4.0-22 errors
4.4.0-72 errors
4.4.0-75 errors