linux-kernel - Re: Linux 2.6.21-rc6

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Message-Id: <200704151753.00584.rjw@sisk.pl>
Date:	Sun, 15 Apr 2007 17:52:59 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Dmitry Torokhov <dtor@...ightbb.com>,
	Tobias Diedrich <ranma+kernel@...edrich.de>
Cc:	pavel@...e.cz, Adrian Bunk <bunk@...sta.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-pm@...ts.osdl.org, Maxim Levitsky <maximlevitsky@...il.com>
Subject: Re: Linux 2.6.21-rc6

On Sunday, 15 April 2007 16:19, Dmitry Torokhov wrote:
> On Sunday 15 April 2007 07:16, Rafael J. Wysocki wrote:
> > On Sunday, 15 April 2007 10:02, Tobias Diedrich wrote:
> > 
> > > > With CONFIG_PM_DEBUG=y and CONFIG_DISABLE_CONSOLE_SUSPEND=y I see
> > > > that the second suspend hangs at "i8042 i8042: EARLY resume".
> > > > This is kinda interesting because I'm normally using a USB keyboard
> > > > and sure enough, if I hook up a normal keyboard and disable USB
> > > > legacy support in the BIOS, then suspend to disk works multiple
> > > > times. I'd still rather like to use my USB keyboard though. ;)
> > 
> > Well, I think that when you're using the USB keyboard and the USB legacy
> > support, the i8042 driver thinks it has a keyboard to handle and tries to
> > handle it during the suspend, which fails.  I don't know why it fails during
> > the second suspend, though.
> > 
> > Dmitry, could you please have a look?
> > 
> 
> This is wierd as i8042 does not use suspend_late/resume_early hooks and
> so it is impossible for it to hang there. None of input drivers use these
> hooks. Could it be that some other driver _after_ i8042 hangs?

Yes.

Tobias, can you please post the dmesg output from after a successful
suspend/resume cycle with CONFIG_PM_DEBUG=y in the 'platform' mode?

> > > And I can now confirm that unpatched 2.6.21-rc6 works fine as long
> > > as USB legacy support is disabled (however without legacy support I
> > > can't use the USB keyboard to control grub).
> > 
> > I think using the 'shutdown' mode of suspend would be better.  There's a little
> > point in using 'platform' on desktop systems anyway.
> > 
> > Frankly, I don't know what to do about it.  If we move platform_finish() after
> > device_resume(), some systems may be broken and I think there are more such
> > systems than there are systems that set USB legacy support in the BIOS and
> > have no PS/2 keyboards attached.
> 
> I would say that every box that does not use PS/2 keyboard does this.

Quite some people I know use USB keyboards with notebooks, but in these cases
the PS/2 keyboard is still attached (except for notebooks in which the built-in
keyboard is a USB one, that is).

> IOW every box with USB keyboard has legacy emulation turned on so quite
> few of them...

I have such a machine nearby, so I'll see if I can reproduce the problem.

Greetings,
Rafael

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