pstate_idle is broken on 4.1, high fan speed when idle

[Daniel Kessel]

The system has high fan speed even when idle. Overall, the fan never gets to a fan speed as low as with the 3.13 kernel.

When running the kernel with intel_pstate=disable, i get much more governor choices, and when selecting "powersave" with this, i get much better behavior, just as with the 3.13 kernel.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: linux-image-4.1.0-3-generic 4.1.0-3.3
ProcVersionSignature: Ubuntu 4.1.0-3.3-generic 4.1.3
Uname: Linux 4.1.0-3-generic x86_64
ApportVersion: 2.18-0ubuntu6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: daniel 1764 F.... pulseaudio
CurrentDesktop: XFCE
Date: Thu Aug 13 19:29:31 2015
HibernationDevice: RESUME=UUID=46d75d9b-22b0-497f-b169-c644d6e0df61
InstallationDate: Installed on 2015-02-05 (188 days ago)
InstallationMedia: Xubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150205)
MachineType: Dell Inc. Dell System XPS L502X
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.1.0-3-generic root=UUID=2f827672-ff82-4172-b6cc-5235e95473e8 ro quiet splash intel_pstate=disable
RelatedPackageVersions:
 linux-restricted-modules-4.1.0-3-generic N/A
 linux-backports-modules-4.1.0-3-generic N/A
 linux-firmware 1.146
SourcePackage: linux
UpgradeStatus: Upgraded to wily on 2015-05-28 (76 days ago)
dmi.bios.date: 10/20/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A07
dmi.board.name: 0NJT03
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: 0.1
dmi.modalias: dmi:bvnDellInc.:bvrA07:bd10/20/2011:svnDellInc.:pnDellSystemXPSL502X:pvr:rvnDellInc.:rn0NJT03:rvrA00:cvnDellInc.:ct8:cvr0.1:
dmi.product.name: Dell System XPS L502X
dmi.sys.vendor: Dell Inc.

[Daniel Kessel (dkessel)]

I ran the system with intel_pstate=disable when filing the bug, but the buggy behaviour is without that option.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.2 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.2-rc7-unstable/

[Daniel Kessel (dkessel)]

Indeed. The 4.2-rc7 kernel allows the fan to spin down so low that I cannot hear it anymore. This seems fixed in 4.2