Date:	Tue, 2 Jun 2009 00:42:36 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jan Scholz <scholz@...s.uni-frankfurt.de>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Adrian Bunk <bunk@...nel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [regression, bisected] adb trackpad disappears after suspend to ram

On Tuesday 02 June 2009, Jan Scholz wrote:
> "Rafael J. Wysocki" <rjw@...k.pl> writes:
> 
> > On Monday 01 June 2009, Jan Scholz wrote:
> >> "Rafael J. Wysocki" <rjw@...k.pl> writes:
> >> 
> >> > On Friday 29 May 2009, Jan Scholz wrote:
> >> >> Benjamin Herrenschmidt <benh@...nel.crashing.org> writes:
> >> >> 
> >> >> >> We are too late in the cycle to revert this commit and it really is needed to
> >> >> >> fix a more serious issue.  Nevertheless knowing that it caused the problem to
> >> >> >> appear on your system is also important.
> >> >> >> 
> >> >> >> Ben, do you have an idea what may be going on here?  Does __disable_irq() mask
> >> >> >> the interrupt on this platform?
> >> >> >
> >> >> > I suppose so :-) I'll have to check what's going on, it's not
> >> >> > immediately clear to me.
> >> >> >
> >> >> > Cheers,
> >> >> > Ben.
> >> >> >
> >> >> >> 
> >> >> >> I'd like to see a boot log, preferably containing a suspend-resume in which
> >> >> >> the problem was reproduced.
> >> >> 
> >> >> Here is a log from booting, through several suspend cycles, until the
> >> >> trackpad disappeared. The first few suspends were done while X was
> >> >> running but from the console. As you can tell from lines like
> >> >>    May 28 23:51:26 [kernel] adb devices: [2]: 2 c4 [3]: 3 1 [7]: 7 1f
> >> >> the trackpad was still present. The last suspend was done from within X,
> >> >> here the trackpad did not make it.
> >> >>    May 28 23:58:09 [kernel] adb devices: [2]: 2 c4 [7]: 7 1f
> >> >> However, there have been cases, although not in this log, were the
> >> >> trackpad has been alive even when suspending from within X.
> >> >
> >> > This means the problem is probably timing-related.
> >> >
> >> > Can you please try to comment out suspend_device_irqs() and
> >> > resume_device_irqs()  in drivers/base/power/main.c and see if that changes
> >> > anything?  It's not entirely safe (well, that's why the calls are there after
> >> > all), but hopefully the box won't hang during this test.
> >> >
> >> 
> >> Tried that against v2.6.30-rc7 and it seems to fix the issue. I did ~10
> >> suspend-resume cycles from the console (which worked just like before)
> >> and ~20 cycles from within X and the trackpad is still alive.
> >
> > So, it seems we lose and interrupt during resume and that confuses the
> > ADB controller driver or something like this.  Do you use the keyboard or
> > the trackpad as a wake-up device?
> 
> I do the wakeup by pressing keys on the keyboard. I'd try wakeup via the
> trackpad's button, but I have no idea how to activate that.
> 
> > Please additionally try to go back to the original code, put
> > 'sleepy_trackpad = 1' at the beginning of do_adb_reset_bus() in
> > drivers/macintosh/adb.c and see if the problem is reproducible with that.
> 
> Tried this, but it does not help.
> 
> What I haven't noticed before is, that even if the trackpad already
> disappeared, an additional suspend-resume cycle from the console brought
> it back to life every time. Sometimes this worked from within X as well,
> just not with such a high probability as from the console.
> However, this is independent from 'sleepy_trackpad = 1'. 

OK, thanks for testing.  I think I know what to do, but I need some time to
prepare a patch.

Best,
Rafael
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