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Tasklist

FS#28151 - [linux] Please select CONFIG_X86_SPEEDSTEP_CENTRINO

Attached to Project: Arch Linux
Opened by Andrej Podzimek (andrej) - Sunday, 29 January 2012, 07:31 GMT
Last edited by Tobias Powalowski (tpowa) - Wednesday, 22 February 2012, 16:46 GMT
Task Type Feature Request
Category Packages: Core
Status Closed
Assigned To Tobias Powalowski (tpowa)
Thomas Bächler (brain0)
Architecture i686
Severity Very Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 1
Private No

Details

Description:

I know this option is deprecated. However, frequency scaling on my ancient Asus M2N (and a variety of other early Centrino laptops) will not work without the speedstep-centrino kernel module loaded. Perhaps a separate package for these deprecated modules could be created.

I haven't noticed this issue for quite a long time, since I used to build my own vanilla kernels on all machines I maintain (-march=native and the like). However, GCC is becoming too sophisticated (and too slow), so this is not feasible any longer.

Steps to reproduce:

Try to enable frequency scaling on an old (2003-2006) Centrino laptop with the default kernel. It won't work.
This task depends upon

Closed by  Tobias Powalowski (tpowa)
Wednesday, 22 February 2012, 16:46 GMT
Reason for closing:  Upstream
Comment by Dan McGee (toofishes) - Tuesday, 31 January 2012, 00:22 GMT
AFAIK this frequency scaling is completely bogus and doesn't really save power. Is this incorrect? There is a reason it was deprecated if so.
Comment by Andrej Podzimek (andrej) - Tuesday, 31 January 2012, 11:46 GMT
This frequency scaling seemed to work fine on the laptop since 2004. :-) I don't know whether it is bogus or not, but reducing the CPU frequency from 1600 MHz down to 600 MHz (and reducing core voltage accordingly) might save some power. (This is what speedstep-centrino can do.) I don't have a power meter to verify that power consumption actually drops.

The ArchLinux WiKi says [https://wiki.archlinux.org/index.php/CPU_Frequency_Scaling#CPU_frequency_driver]:
"acpi-cpufreq CPUFreq driver which utilizes the ACPI Processor Performance States. This driver also supports Intel Enhanced Speedstep (previously supported by the deprecated speedstep-centrino module)."

This is wrong, at least for Asus M2N. The acpi-cpufreq module does not work (and does not even load) on the machine. Loading the module terminates with an error state (1), but *no* log messages are produced and (of course) the module does not appear in lsmod. The acpi_pstate_strict parameter does not seem to change anything.
Comment by Dan McGee (toofishes) - Tuesday, 31 January 2012, 11:54 GMT
You're much better off reporting a bug against that driver. I see no reason why we should re-enable some deprecated driver in our kernel only to work around something broken in the designated replacement. I would highly recommend contacting upstream and seeing what info they need to debug the problem.

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