Date: Wed, 19 Mar 2008 08:54:38 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-arch@freebsd.org Cc: bzeeb-lists@lists.zabbadoz.net, Poul-Henning Kamp <phk@phk.freebsd.dk>, arch@freebsd.org Subject: Re: Power-Mgt Message-ID: <200803190854.39131.jhb@freebsd.org> In-Reply-To: <8726.1205926183@critter.freebsd.dk> References: <8726.1205926183@critter.freebsd.dk>
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On Wednesday 19 March 2008 07:29:43 am Poul-Henning Kamp wrote: > In message <20080319.051604.63052713.imp@bsdimp.com>, "M. Warner Losh" writes: > >In message: <20080318085804.I50685@maildrop.int.zabbadoz.net> > > > > "Bjoern A. Zeeb" <bzeeb-lists@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. > */ That is something to be fixed in the USB driver, but yes. Changing the USB driver to power down when nothing is plugged in may help. -- John Baldwin
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