From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: In-Reply-To: <20070809212420.GD13921@localdomain> References: <20070809005044.GD10114@localdomain> <20070809030555.GA8261@localhost.localdomain> <20070809041632.GA13921@localdomain> <40561246eaa06210a2a607aa7ed67b02@kernel.crashing.org> <20070809212420.GD13921@localdomain> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <6681fdad128303fc62c86c2345aa33a4@kernel.crashing.org> From: Segher Boessenkool Subject: Re: [RFC/PATCH] remove gratuitous reads from maple pci config space methods Date: Fri, 10 Aug 2007 19:58:43 +0200 To: Nathan Lynch 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: , >>> 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. Yes. Of course, as usual, testing is needed, yada yada. >>> 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. It should be fine on PowerMac as well -- all G5s use U3/U4, the workaround is for certain older Apple bridge chips. Segher