Power off for PCI devices
johannes.hofmann at gmx.de
Thu Sep 11 09:21:39 PDT 2008
Hasso Tepper <hasso at estpak.ee> wrote:
> Johannes Hofmann wrote:
>> Ah ok. Is there a way to verify the state of the pci devices?
>> On my T42 thinkpad I don't see any difference in power consumption
>> with hw.pci.do_power_nodriver=1 (measured with an external device and
>> battery removed). I'm always around 20 Watt, with est enabled,
>> "DynamicClocks" "on" in xorg.conf, and screen backlight set to the
>> lowest possible value.
> I use hw.pci.do_power_nodriver=3, btw, but it shouldn't matter much. Is
> there unused devices at all? And these devices have to have power
> management capabilities, not all PCI devices have these.
> I use sysutils/pciutils from pkgsrc to play with PCI configuration space.
> It doesn't compile in DragonFly without the patch, pkgsrc bugreport is
> there about year or so :(. Take patch is available at . lspci -vvv
> shows to you all devices with decoded configuration space. For example
> ABOUT my wireless card it shows this:
> Capabilities:  Power Management version 2
> Flags: PMEClk- DSI- D1+ D2- AuxCurrent=375mA
> Status: D3 PME-Enable- DSel=0 DScale=0 PME-
> Important bit is "Status: D3" - ie. this device is powered down.
lspci -vv indeed shows some devices (usb controller, sound card, ethernet card,
and modem) in D3 state.
>  -
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