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Date:      Mon, 04 May 2009 12:51:05 +0300
From:      Alexander Motin <mav@FreeBSD.org>
To:        "Paul B. Mahol" <onemda@gmail.com>
Cc:        FreeBSD acpi <freebsd-acpi@freebsd.org>, FreeBSD-Current <freebsd-current@freebsd.org>, freebsd-mobile@freebsd.org
Subject:   Re: Fighting for the power.
Message-ID:  <49FEBA89.4040609@FreeBSD.org>
In-Reply-To: <3a142e750905040240g58152e69p6fcb797a5e026426@mail.gmail.com>
References:  <49FE1826.4060000@FreeBSD.org> <3a142e750905040240g58152e69p6fcb797a5e026426@mail.gmail.com>

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Paul B. Mahol wrote:
> On 5/4/09, Alexander Motin <mav@freebsd.org> wrote:
>> 2. PCI devices
>> PCI bus provides method to control device power. For example, I have
>> completely no use for my FireWire controller and most of time - EHCI USB
>> controller. Disabling them allows me to save about 3W of power. To
>> disable all unneeded PCI devices you should build kernel without their
>> drivers and add to loader.conf:
>> hw.pci.do_power_nodriver=3
>> To enable devices back all you need to do is just load their drivers as
>> modules.
> 
> Unloading modules doesnt put them back into into D3 state.
> You are forced to load some another module again to put wanted device
> into D3 state.

Yes. Resume also does not powers down unowned devices. Would be good to 
fix that also.

-- 
Alexander Motin



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