linux-kernel - Re: [PATCH] acpi: Avoid dropping rapid hotkey events (or other GPEs) on Asus EeePC

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Message-ID: <487F6D2E.2040501@tuffmail.co.uk>
Date:	Thu, 17 Jul 2008 17:02:54 +0100
From:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
To:	Alexey Starikovskiy <astarikovskiy@...e.de>
CC:	linux-acpi@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] acpi: Avoid dropping rapid hotkey events (or other GPEs)
 on Asus EeePC

Alexey Starikovskiy wrote:
> Hi Alan,
>
> Could you please test if your patch works with the last patch in #10919?
>
> Thanks,
> Alex.
Vacuously so.

My patch still applies, but #10919 makes it obsolete.  My patch fixed a
bug that shows up in polling mode.  #10919 kills polling mode.

I've tested v2.6.26 + #10919 and it works fine (except for spamming the
kernel log - please read my Bugzilla comment).

It appears that interrupt mode suffered from a race which is very
similar to my original problem.  If two GPE interrupts arrive before the
workqueue runs, then the second interrupt will be ignored because
EC_FLAGS_QUERY_PENDING is still set.  This will happen with any EC if
interrupts are very close together, right?

I think my patch also fixes this theoretical problem.  But I'd rather
you took over on this.  I was already confused by ec.c in v2.6.26, and
with #10919 I understand it even less.  E.g. why is
ec_switch_to_poll_mode() still present; what does it do now do_ec_poll()
is removed?

I'm happy to work on this with you, but I'd need to be able understand
the code first :-(.

Alan
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