From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lixom.net (lixom.net [66.141.50.11]) by ozlabs.org (Postfix) with ESMTP id E4917DDE21 for ; Sat, 5 Apr 2008 04:53:42 +1100 (EST) Date: Fri, 4 Apr 2008 13:03:33 -0500 From: Olof Johansson To: Segher Boessenkool Subject: Re: [PATCH] PowerPC: MPIC ack interrupts at mpic_teardown_this_cpu() Message-ID: <20080404180333.GB26693@lixom.net> References: <20080403190943.GA16446@ru.mvista.com> <1207259436.10388.337.camel@pasglop> <20080404052955.GC11799@lixom.net> <9d19fecb0ef172995b7ce3a317ee3c0d@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <9d19fecb0ef172995b7ce3a317ee3c0d@kernel.crashing.org> Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 >>>> --- >>> >>> 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 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