Re: [linux-pm] [patch] pm: fix runtime powermanagement's /sys interface

Pavel Machek
2006-01-05T22:23:38Z

On Čt 05-01-06 23:13:34, Dominik Brodowski wrote:
> On Thu, Jan 05, 2006 at 10:55:29PM +0100, Pavel Machek wrote:
> > > I have a firewire controller in a desktop system, and a ATI Radeon in a
> > > T42 that support D1 and D2..
> >
> > Ok, now we have a concrete example. So Radeon supports D1. But putting
> > radeon into D1 means you probably want to blank your screen and turn
> > the backlight off; that takes *long* time anyway. So you can simply
> > put your radeon into D3 and save a bit more power.
>
> Using your logic, you never want to put your CPU into C2 power-saving state
> instead of C3 or C4. Which is ridiculous. There are technical reasons why
> you want to put devices into different power-saving states. E.g. wakeup
> latency, ability to receive wakeup signals, snooping and so on.

Well, yes. Two years before we supported hlt, it would be stupid to
try to support multiple hlt states. We do not support hlt for any
devices today.

> In addition, your patch breaks pcmcia / pcmciautils which already uses
> numbers (which I already had to change from "3" to "2" before...).

pcmcia actually uses this? Ouch. Do you just read the power file, or
do you write to it, too?
Pavel

--
Thanks, Sharp!