linux-kernel - Re: "ACPI: EC: missing confirmations, switch off interrupt mode" wastes time on startup

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Date:	Thu, 26 Mar 2009 22:54:07 +0100
From:	Corrado Zoccolo <czoccolo@...il.com>
To:	Alan Jenkins <sourcejedi.lkml@...glemail.com>
Cc:	linux-kernel@...r.kernel.org,
	linux acpi <linux-acpi@...r.kernel.org>
Subject: Re: "ACPI: EC: missing confirmations, switch off interrupt mode" 
	wastes time on startup

On Thu, Mar 26, 2009 at 5:58 PM, Alan Jenkins
<sourcejedi.lkml@...glemail.com> wrote:
> On 3/26/09, Corrado Zoccolo <czoccolo@...il.com> wrote:
>
> [CC linux-acpi]
>
> Thanks for reporting this bug / issue.  Your hardware is probably
> defective by design - that is, it doesn't follow the ACPI spec.  But
> we can't blame users for that :-).
>
> I take it this isn't a regression, i.e. if you've tried earlier
> kernels, it's never worked any better?

This is new hardware, and 2.6.29 is the first kernel I installed, so I
can't say.

>
> You say this is a severe delay - but your logs show 0.5 seconds only,
> is that right?  Just to get it clear.
>
Right, but Arjan showed that 1s boot time for kernel is possible, so
0.5s is quite severe respect to this :).
I'm still way far from 1s, though, due to an other issue that wastes
>1s, i.e. tsc clocksource unstable.

> Currently there is no option to force polling, sorry.  I'm _guessing_
> this was a deliberate omission.  But I can sympathise that even 0.5s
> boot delay is bad on a netbook.
>
Yes. Do you think that changing olpc_ec_timeout kernel parameter may
help in getting the timeout sooner?

> Feel free to create a new bugzilla entry.  You can attach the full
> output of dmesg, but acpidump is probably not required.  What would be
> really helpful is if you could file on bugzilla, and attach a full
> debug trace.  I.e. as well as the normal dmesg, attach the dmesg
> output after recompiling with this change:
>

bug: http://bugzilla.kernel.org/show_bug.cgi?id=12949
full debug dmesg: http://bugzilla.kernel.org/attachment.cgi?id=20695

Thanks,
Corrado

-- 
__________________________________________________________________________

dott. Corrado Zoccolo                          mailto:czoccolo@...il.com
PhD - Department of Computer Science - University of Pisa, Italy
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