[ltp] missing C4 power state on core duo (x60s)

[Kevin O'Brien]

Martin Aumueller-3 wrote:
> 
> No C4 here either on a X60s with BIOS 1.04. And neither when on battery.
> 
> However, as opposed to almost never it now manages to enter C3 quite often
> - 
> and then it emits the well-known noise. That is probably due to the fact
> that 
> /proc/acpi/processor/CPU0/power never shows
> bus master activity:     00000000
> when the ohci_hci driver is loaded. This is probably the reason for the
> lower 
> power consumption with BIOS 1.04.
> 
> Martin
> 

Thanks Martin,
It seems i was wrong about the newer BIOS preventing the sleep state.

I also get bus master activity: 00000000 when i unload the low speed usb
driver (uhci_hcd in this case) with BIOS 1.06, although i get no noise. 

I noticed on both the Linux Thinkpad threads "X60s: Heat, power management,
battery" and "Maximum Battery Capacity of an T60 under Linux"  that whenever
someone posts the contents of /proc/acpi/processor/CPU0/power for a Core Duo
processor the C4 power state is always absent. 

Does anyone have a core duo processor in any laptop where the C4 power state
shows up in /proc/acpi/processor/CPU0/power ?

Also, does anyone know why the C4 power state shows up for the Pentium M
(Dothan) and not for the Core Duo (Yonah) when both are capable of this
state?
Could this be an issue with the speedstep driver in the kernel?

Thanks,
Kevin
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