Re: [PATCH] implement pm_ops.valid for everybody

Rafael J. Wysocki
2007-03-22T21:37:48Z

On Thursday, 22 March 2007 20:26, Tony Lindgren wrote:
> Hi,
>
> * David Brownell <david-b@pacbell.net> [070322 14:30]:
> > On Thursday 22 March 2007 6:44 am, Scott E. Preece wrote:
> > > | From: "Rafael J. Wysocki" <rjw@sisk.pl>
> > > |
> > > | I think we can define "standby" a bit more precisely. Something like:
> > > | - processes are frozen,
> > > | - devices are suspended,
> >
> > True of all sleep states, although one wants "suspended" to
> > allow different levels of device functionality. (Maybe it
> > can wake up, maybe its firmware is monitoring the WLAN, etc.)
>
> In addition to offering wakeup events for individual devices,
> the device suspend states should be something like retention
> and suspend, where:
>
> Retention is where clocks are off for a device, but power is on.
> In this case the device registers are maintained in hardware.
>
> Suspend is where clocks and power are off. In this state the
> device registers are maintained in software.
>
> Laptops mostly have suspend, while socs allow both retention
> and suspend in many cases.

I think there can be more low-power states that just "standby",
"STR", "STD", etc., but for example "standby" should be at least comparable
between different platforms.

Greetings,
Rafael