Bug 42875

Summary:	dell m4600 cpu speed limit by a special bios_limit
Product:	ACPI	Reporter:	Hui Zhu (teawater)
Component:	Config-Processors	Assignee:	Zhang Rui (rui.zhang)
Status:	CLOSED INSUFFICIENT_DATA
Severity:	normal	CC:	aaron.lu, alan, kedgedev, rui.zhang, tianyu.lan
Priority:	P1
Hardware:	All
OS:	Linux
URL:	https://bugs.launchpad.net/linux/+bug/819605
Kernel Version:	any	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	cpu freq grep acpidump

Description Hui Zhu 2012-03-06 14:20:16 UTC

In this link, there are a lot of people's m4600 got cpu speed is limit by a special number in bios_limit.

And I tried this issue in upstream, 3.2 and 2.6.x.  All of them affect by this issue.


And this issue can be handle by add "processor.ignore_ppc=1" to command line.

Comment 1 Zhang Rui 2012-11-28 10:31:33 UTC

so in what situation when you get the bios_limit?
does it happen when you boot with battery or when you remove the power supply?

please attach the acpidump output of the laptop.
please attach the output of "grep . /sys/devices/system/cpu/cpu*/cpufreq/*"

Comment 2 Zhang Rui 2012-12-11 01:45:17 UTC

ping...

Comment 3 Roman Jarosz 2013-01-28 20:12:01 UTC

I think than I have similar problem.
IMHO since kernel 3.7 when I start notebook without power supply, the cpu frequency is stuck on lowest speed, 3.8_rc5 is also broken.

Comment 4 Roman Jarosz 2013-01-28 20:12:26 UTC

Created attachment 92051 [details]
cpu freq grep

Comment 5 Roman Jarosz 2013-01-28 20:13:49 UTC

Created attachment 92061 [details]
acpidump

Comment 6 Aaron Lu 2013-07-08 05:21:50 UTC

(In reply to Roman Jarosz from comment #3)
> I think than I have similar problem.
> IMHO since kernel 3.7 when I start notebook without power supply, the cpu
> frequency is stuck on lowest speed, 3.8_rc5 is also broken.

Does v3.6 have this problem?

AFAIK, if _PPC as provided by firmware told us now the CPU's frequency can't be higher than 800MHZ, then Linux will follow it. THe behavior can be changed by the above mentioned ignore_ppc kernel command line, or you can use intel_pstate cpu frequency driver instead.

Comment 7 Lan Tianyu 2013-08-06 06:41:56 UTC

any update? Does intel_pstate work?

Comment 8 Zhang Rui 2013-10-14 10:40:40 UTC

Bug closed as there is no reponse from the bug reporter.
please feel free to reopen it if you can reproduce the problem in latest upstream kernel and provide the information requested in comment #7.