linux-kernel - Re: [linux-pm] Async suspend-resume patch w/ completions (was: Re: Async?suspend-resume patch w/ rwsems)

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Date:	Sun, 20 Dec 2009 23:39:15 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-pm@...ts.linux-foundation.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Vojtech Pavlik <vojtech@...e.cz>
Subject: Re: [linux-pm] Async suspend-resume patch w/ completions (was: Re:
	Async?suspend-resume patch w/ rwsems)

On Sun, Dec 20, 2009 at 08:25:25PM +0100, Rafael J. Wysocki wrote:
> On Sunday 20 December 2009, Dmitry Torokhov wrote:
> > On Sat, Dec 19, 2009 at 04:09:07PM -0800, Linus Torvalds wrote:
> > > 
> > > That said, I still get the feeling that we'd be even better off simply 
> > > trying to avoid the whole keyboard reset entirely. Apparently we do it for 
> > > a few HP laptops.
> > 
> > I was mistaken, HP laptops do not like mouse disabled when suspending,
> > not sure about the rest of the state.
> > 
> > > It's entirely possible that we'd be better off simply 
> > > not _doing_ the slow thing in the first place.
> > >
> > 
> > The reset appeared first in 2.5.42. I expect that some BIOSes get very
> > confused when tehy find mouse speaking something that they do not
> > unserstand (i.e. synaptics, ALPS or anything else that is not bare PS/2
> > or intellimouse), but maybe Vojtech remembers better?
> >  
> > > For example, we may be _much_ better off doing that whole keyboard reset 
> > > at resume time than at suspend time.
> > 
> > We do the reset for the different reasons - at resume we want the device
> > in known state to ensure that it properly responds to the probes we
> > send to it. At suspend we trying to reset things into original state so
> > that the firmware will not be confused.
> > 
> > If we want to try to live without reset we could to PSMOUSE_CMD_RESET_DIS
> > instead of PSMOUSE_CMD_RESET_BAT which is much heavier. We should
> > probably not wait for .34 then because the bulk of testing will happen
> > only when .33 is close to be released because that's when most of
> > regular users will start using the new code and try to suspend and
> > resume.
> > 
> > Rafael, how long does suspend take if you change call to psmouse_reset()
> > in psmouse_cleanup() to ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_RESET_DIS)?
> > And do the same for atkbd...
> 
> On the nx6325 that appears to reduce the suspend time as much so the effect
> of async is not visible any more.  On the Wind it decreases the total suspend
> time almost by half!
> 
> Please push this patch to Linus. :-)
> 

Let's see if I manage to solicit some testers first. FWIW it seems to be
working on my boxes.

But if this works then I am not sure we even want to bother with async
suspend of i8042 and serios. And serio already does resume
asynchronously through kseriod.

-- 
Dmitry
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