From: Olof Johansson <olof@lixom•net>
To: Segher Boessenkool <segher@kernel•crashing.org>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] PowerPC: MPIC ack interrupts at mpic_teardown_this_cpu()
Date: Fri, 4 Apr 2008 13:03:33 -0500 [thread overview]
Message-ID: <20080404180333.GB26693@lixom.net> (raw)
In-Reply-To: <9d19fecb0ef172995b7ce3a317ee3c0d@kernel.crashing.org>
On Fri, Apr 04, 2008 at 07:38:27PM +0200, Segher Boessenkool wrote:
>>>> We really need to ack interrupts at mpic_teardown, since
>>>> not all platforms reset mpic at kernel start-up. For example,
>>>> kexec'ed kernel hangs on P.A. Semi if mpic_eoi() isn't called.
>>>>
>>>> Signed-off-by: Valentine Barshak <vbarshak@ru•mvista.com>
>>>> ---
>>>
>>> Would be interesting to find out why it hangs tho... it shouldn't .
>>
>> I haven't reproduced the problem and looked at hardware state yet, but
>> I
>> would expect it to be because the openpic won't send another interrupt
>> until the previous is EOI'd, and the IPI is never EOI'd as far as I
>> can tell.
>>
>> The XICS code does it explicitly already. I'm surprised it doesn't
>> break
>> on the 970-based platforms actually...
>
> platforms/maple/setup.c and platforms/powermac/pic.c use
> MPIC_WANTS_RESET.
> Is there a reason why we don't do that on every MPIC? If there is such
> a reason, the default should be to reset, only pseries and chrp and cell
> and now pasemi do not use it. It's the only sane way to get an MPIC
> into
> a sane known state starting from <whatever> state.
I used to have the reset there on pasemi but due to some other issues I
ended up taking it out.
It's not like doing a final EOI is a big deal, I really don't see why
there's hassle about this patch.
-Olof
next prev parent reply other threads:[~2008-04-04 17:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-03 19:09 [PATCH] PowerPC: MPIC ack interrupts at mpic_teardown_this_cpu() Valentine Barshak
2008-04-03 21:50 ` Benjamin Herrenschmidt
2008-04-04 5:29 ` Olof Johansson
2008-04-04 17:38 ` Segher Boessenkool
2008-04-04 18:03 ` Olof Johansson [this message]
2008-04-04 18:55 ` Segher Boessenkool
2008-04-04 19:39 ` Olof Johansson
2008-04-07 14:24 ` Olof Johansson
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