From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from kcout01.prserv.net (kcout01.prserv.net [12.154.55.31]) by ozlabs.org (Postfix) with ESMTP id DB073DDEFA for ; Sat, 8 Sep 2007 00:16:31 +1000 (EST) In-Reply-To: <20070907092143.GB32102@lixom.net> References: <20070905024417.GE27139@lixom.net> <20070907092143.GB32102@lixom.net> Mime-Version: 1.0 (Apple Message framework v624) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <326829233f0e99b0e0404241f5faaa7a@bga.com> From: Milton Miller Subject: Re: [PATCH v2] powerpc: Add workaround for MPICs with broken register reads Date: Fri, 7 Sep 2007 09:11:52 -0500 To: Olof Johansson Cc: paulus@samba.org, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sep 7, 2007, at 4:21 AM, Olof Johansson wrote: > Some versions of PWRficient 1682M have an interrupt controller in which > the first register in each pair for interrupt sources doesn't always > read with the right polarity/sense values. > > To work around this, keep a software copy of the register instead. > Since > it's not modified from the mpic itself, it's a feasible solution. > Still, > keep it under a config option to avoid wasting memory on other > platforms. > > Signed-off-by: Olof Johansson > > > diff --git a/arch/powerpc/platforms/Kconfig > b/arch/powerpc/platforms/Kconfig > index 041df77..f2e7049 100644 > --- a/arch/powerpc/platforms/Kconfig > +++ b/arch/powerpc/platforms/Kconfig > @@ -137,6 +137,18 @@ config MPIC_U3_HT_IRQS > depends on PPC_MAPLE > default y > > +config MPIC_BROKEN_REGREAD > + bool "MPIC workaround for broken register reads" > + depends on MPIC > + help > + Say Y here to enable a MPIC driver workaround for some chips that > + have a bug that causes some interrupt source information to not > + read back properly. It is safe to use on other chips as well, but > + enabling it uses about 8KB of memory to keep copies of the register > + contents in software. > + > + Say N if you are unsure. > + > I'm sorry, I didn't mean to imply it should be asked / selectable, just that the help should be provided. I won't object to leaving it except that it asks the average user unnecessary questions. In other words, drop the question after bool. milton