linux-kernel - Re: Zaurus suspend saga

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Date:	Mon, 7 Sep 2009 13:31:32 +0200
From:	Pavel Machek <pavel@....cz>
To:	Richard Purdie <rpurdie@...ys.net>
Cc:	lenz@...wisc.edu, kernel list <linux-kernel@...r.kernel.org>,
	Dirk@...er-Online.de, arminlitzel@....de,
	Cyril Hrubis <metan@....cz>, thommycheck@...il.com,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>,
	dbaryshkov@...il.com, omegamoon@...il.com, eric.miao@...vell.com,
	utx@...guin.cz
Subject: Re: Zaurus suspend saga

Hi!

> > fatal reads invalid values -- -108 -- probably because spi is not ready?
> > 
> > is spi suspend/resume required? yes.; and yes spi is resumed too late
> >  in the sequence. Or perhaps fatal battery check is way too early.
> > 
> > Could someone confirm that simply removing sharpsl_fatal_check() fixes
> > zaurus suspend on 2.6.31? 
> 
> Sadly lack of time means I've lost track of the Zaurus kernels but this
> sounds like all accesses to the SSP buses now go through the SPI layer
> and when it was converted nobody thought about the impact this would
> have on the Zaurus charger code.

Unfortunately... Do you have any idea when this conversion took place?

> If suspend/resume is broken in this way, it also means the charger code
> is also likely to be totally broken/malfunctioning since it won't be
> able to read from the ADC either.

Yes. Seems like low-level zaurus code is FUBAR.

> Either:
> 
> a) Someone steps up and finds a way to partially resume the kernel so
> the "offline" charging code can work and access SPI

> b) We find some other way to allow the SPI interface to be accessed by
> the charger code without resuming the whole kernel (the way it used to
> work)

Doing that in a hacky way should be rather easy... just calling spi
resume manually. But...

> c) We rip the whole thing out and stop supporting "offline" charging.

How much faster is offline charge, compared to online charging? I have
impression that online charging basically does not charge anything...

> I'd hate to see c) happen but I doubt I'm going to find time to rewrite
> that code any time soon and nobody else even seems to have grasped how
> deep this problem really is :(.

Well, I have a bit of time now and then...
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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