Dell Latitude E7240 does not resume from suspend with non-default BIOS settings (when serial port is disabled?)

[Rob Day]

Seen with 14.04 beta 1 (Trusty).

When I suspend my Dell Latitude E7240 laptop (either by closing the lid, running pm-suspend or selecting Sleep from the KDE menu) it suspends successfully and the power LED flashes. When I try and resume it (either by opening the laptop or by pressing the power button), it starts to resume (the power button stops flashing and is fully lit up) but nothing appears on the screen and my wifi indicator starts flashing (on for ~4 seconds, off for ~4 seconds) until I power off the machine by holding the power button down.

I've reproduced this with linux-image-3.14.0-031400rc7-generic (the latest non-nightly kernel mainline), as recommended by https://wiki.ubuntu.com/DebuggingKernelSuspend. I've also booted into the 12.04 Kubuntu install CD and suspended that, which experiences the same problem.

I'm using the latest BIOS (A08). I'm reasonably confident this isn't a problem with my wifi card - I experience the same symptoms when it is disabled in the BIOS or switched off by the hardware switch.

I've followed the pm_trace instructions at https://wiki.ubuntu.com/DebuggingKernelSuspend and attached it. That does include the lines:

[ 1.458151] Magic number: 6:635:599
[ 1.458165] serial8250 serial8250: hash matches

However, lsmod doesn't show a serial8250 module loaded.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-generic 3.13.0.12.16
ProcVersionSignature: Ubuntu 3.13.0-12.32-generic 3.13.4
Uname: Linux 3.13.0-12-generic x86_64
ApportVersion: 2.13.3-0ubuntu1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: rkd 1765 F.... pulseaudio
                      rkd 2010 F.... pulseaudio
 /dev/snd/controlC0: rkd 1765 F.... pulseaudio
                      rkd 2010 F.... pulseaudio
CurrentDesktop: KDE
Date: Thu Mar 20 21:23:36 2014
HibernationDevice: RESUME=UUID=2e1c8ed9-ac52-4045-a6b2-affdbd3a0594
InstallationDate: Installed on 2014-03-20 (0 days ago)
InstallationMedia: Kubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140227)
MachineType: Dell Inc. Latitude E7240
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-12-generic root=UUID=de5a2758-01bf-4e83-86f3-6eca4f55fdb2 ro rootflags=subvol=@ quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-12-generic N/A
 linux-backports-modules-3.13.0-12-generic N/A
 linux-firmware 1.126
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/18/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A08
dmi.board.name: 0R8R7K
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA08:bd02/18/2014:svnDellInc.:pnLatitudeE7240:pvr01:rvnDellInc.:rn0R8R7K:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E7240
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Was there ever a prior release or kernel that did not experience this issue?

[Joseph Salisbury (jsalisbury)]

Also, this issue appears to be an upstream bug, since you tested the latest upstream kernel. Would it be possible for you to open an upstream bug report[0]? That will allow the upstream Developers to examine the issue, and may provide a quicker resolution to the bug.

Please follow the instructions on the wiki page[0]. The first step is to email the appropriate mailing list. If no response is received, then a bug may be opened on bugzilla.kernel.org.

Once this bug is reported upstream, please add the tag: 'kernel-bug-reported-upstream'.

[0] https://wiki.ubuntu.com/Bugs/Upstream/kernel

[Rob Day (rkd-u)]

No, I've never had this working.

I'm happy to report it upstream - I'll do so in the next few days.

[Rob Day (rkd-u)]

I did some more digging and realised that this was due to a misconfigured BIOS - I'd been too aggressive in disabling hardware to save power. Once I restored it to the default setting, suspend/resume works fine - from the pm_trace logs I suspect the issue was that I'd disabled the serial port.

I'm happy for this bug to be closed, or changed to a lower priority. I'll rename it to reflect the actual bug.