Fighting for the power.

[Paul B. Mahol]

On 5/7/09, M. Warner Losh <imp at bsdimp.com> wrote:
> In message: <3a142e750905040240g58152e69p6fcb797a5e026426 at mail.gmail.com>
>             "Paul B. Mahol" <onemda at gmail.com> writes:
> : On 5/4/09, Alexander Motin <mav at 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.
>
> It should.  If it isn't, that's a bug.

It's a bug.

On machine resume(pci_resume), pci_cfg_restore() is called causing D3 -> D0 for
all devices(including not attached ones).
Unloading module/detaching device doesn't call pci_cfg_save.

Should device_detach routine be used or new one like
pci_driver_removed() implemented?

-- 
Paul