Power-Mgt

[Poul-Henning Kamp]

In message <20080319.051604.63052713.imp at bsdimp.com>, "M. Warner Losh" writes:
>In message: <20080318085804.I50685 at maildrop.int.zabbadoz.net>
>            "Bjoern A. Zeeb" <bzeeb-lists at lists.zabbadoz.net> writes:
>: what actually happens to an unrecognized card or a card with no driver
>: loaded currently? How much power does an unsued card use and can we do
>: anything about that? Are we perhaps already doing something about
>: that?
>
>For PCI it is set into D3 state.  Or at least was until this caused a
>problem with some raid controllers that didn't follow the rules and
>had extra devices that the card used, but that the OS didn't have a
>driver for.
>
>For PC Card, the card is powered down entirely.  For CardBus I think
>the same.  For USB, ugen takes it, and therefore it is powered up.

Not to mention this comment from acpi_cpu.c:

    /*
     * Check for bus master activity.  If there was activity, clear
     * the bit and use the lowest non-C3 state.  Note that the USB
     * driver polling for new devices keeps this bit set all the
     * time if USB is loaded.
     */


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.