From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sceptre.pobox.com (sceptre.pobox.com [207.106.133.20]) by ozlabs.org (Postfix) with ESMTP id E83F0DDF1C for ; Fri, 10 Aug 2007 07:24:39 +1000 (EST) Date: Thu, 9 Aug 2007 16:24:20 -0500 From: Nathan Lynch To: Segher Boessenkool Subject: Re: [RFC/PATCH] remove gratuitous reads from maple pci config space methods Message-ID: <20070809212420.GD13921@localdomain> References: <20070809005044.GD10114@localdomain> <20070809030555.GA8261@localhost.localdomain> <20070809041632.GA13921@localdomain> <40561246eaa06210a2a607aa7ed67b02@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <40561246eaa06210a2a607aa7ed67b02@kernel.crashing.org> Cc: linuxppc-dev@ozlabs.org, Paul Mackerras , David Gibson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Segher Boessenkool wrote: > >>It might be worth checking that there isn't a particular reason for > >>these. Just because posting writes are forbidden doesn't mean a > >>particular bridge won't screw it up... > > > >Well, I had already checked with Ben, who wrote the code, and my > >understanding is that the reads are intended to work around some > >misbehaving Apple bridges, > > None of the PCI interfaces on the U3 or U4 bridges have that > problem as far as I know. I think the workaround was copied > from code for older Apple bridges? Okay, then the change should be fine for maple. > >but that a sync after the write (implied by > >releasing pci_lock in the generic pci code) should suffice for those. > > I don't see how a sync could help here at all, not more than > an eieio anyway? Alright, well, maybe take it up with Ben when I post the patch for powermac, since that's where it could actually matter.