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

Alan Jenkins
2008-08-13T10:21:50Z

Andrew Morton wrote:
> Did this get fixed yet?
>
> I have an patch in -mm which I just restored (I had to tempdrop it
> because the acpi tree was busted for some time). But it seems to be
> old.
>
> http://bugzilla.kernel.org/show_bug.cgi?id=10919 is marked "resolved"
> but the reporter (Maximilian) seems to think otherwise. 2.6.26.x is,
> afaik, still unfixed, as is 2.6.27-rc.
>
That's correct. I think this specific patch should go in 2.6.27 and
2.6.26-stable. No objections have been raised so far.

I still need this patch to make my brightness and volume control keys
usable in 2.6.27-rc3. (They auto-repeat fast enough to trigger the
bug). This is true even after applying the latest patches from bug
10919 (#25 + #27).

I think the 10919 fix makes it harder to reproduce, but it definitely
still happens. I guess this is because the polling-driven EC
transactions add 1ms delays between each byte. The slower timings leave
a window where the buggy behaviour of my EC can make a difference. (It
has been seen to clear the "pending event" bit after a single event is
read, despite having more events pending).

There are more serious consequences of this bug. After a while it can
confuse the EC enough to cause lockups or reboots during boot, or after
pressing a single hotkey. This bad state is preserved over reboots,
even into known good kernels. Fortunately the badness clears when power
is removed for a long enough period. For a while I was worried that
something had physically burnt out.

Thanks
Alan