On Saturday 25 September 2004 8:45 pm, Alan Stern wrote:
> On Sat, 25 Sep 2004, David Brownell wrote:
>
> > In general I think the PM core has to firmly accept the notion
> > of driver-specified device power states ... as things that are
> > distinct from system power states, and that drivers sometimes
> > use to coordinate with each other.
>
> That may be so, but it doesn't mean the PM core has to pay attention to
> what drivers do internally. The core may have its own set of recognized
> state, and drivers may divide each of those into their own private
> sub-states if they like. But you can't expect the core to be aware of the
> idiosyncracies of all the different drivers and devices.
I'd hope the core would focus on system-wide PM policies, an extensible
set that should "at the beginning" include roughly:
- Everything always on. ACPI-friendly. "tune for fastest speeds".
Fair to say this is today's Linux policy default.
- Nothing on unless it needs to be. "tune for least power".
Needs device-specific PM framework improvements, including
wakeup support. Both PCI and USB could use this policy, if
Linux cooperates; also the host system CPU(s).
- Inactive, fast resume: "standby", "big sleep", "suspend-to-ram"
- Inactive, slow resume: "off", "deep sleep", "suspend-to-disk"
Within each of those system-wide policies, any device could have
several compatible device power level. "Least power" should in
some common cases go transparently in and out of "standby",
given wakeup mechanisms that do their jobs.
PMcore shouldn't much care about device power state, in fact ...
maybe not even knowing whether a device's current state is
compatible with the desired system-wide PM policy. That'd
be a big change from today's PMcore framework, though not
necessarily in conflict with whatPavel has written in these threads.
- Dave
-------------------------------------------------------
This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170
Project Admins to receive an Apple iPod Mini FREE for your judgement on
who ports your project to Linux PPC the best. Sponsored by IBM.
Deadline: Sept. 24. Go here: http://sf.net/ppc_contest.php
_______________________________________________
[EMAIL PROTECTED]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
