From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.gna.ch (darkcity.gna.ch [195.226.6.51]) by ozlabs.org (Postfix) with ESMTP id 7CAE3B7380 for ; Wed, 18 Apr 2012 23:08:22 +1000 (EST) Message-ID: <1334754483.5989.309.camel@thor.local> Subject: Re: PowerPC radeon KMS - is it possible? From: Michel =?ISO-8859-1?Q?D=E4nzer?= To: Benjamin Herrenschmidt Date: Wed, 18 Apr 2012 15:08:03 +0200 In-Reply-To: <1334747941.3143.13.camel@pasglop> References: <1334730915.5989.265.camel__41553.0639271767$1334731329$gmane$org@thor.local> <1334736133.5989.278.camel@thor.local> <1334744414.3143.2.camel@pasglop> <1334745292.5989.291.camel@thor.local> <1334745854.5989.295.camel@thor.local> <1334747941.3143.13.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: Andreas Schwab , o jordan , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mit, 2012-04-18 at 21:19 +1000, Benjamin Herrenschmidt wrote:=20 > On Wed, 2012-04-18 at 12:44 +0200, Michel D=C3=A4nzer wrote: > > On Mit, 2012-04-18 at 12:34 +0200, Michel D=C3=A4nzer wrote:=20 > > > On Mit, 2012-04-18 at 20:20 +1000, Benjamin Herrenschmidt wrote:=20 > > > >=20 > > > > I suspect there's a fundamental design issue with apple bridge in t= hat > > > > the CPU to memory path isn't coherent at all with the GPU to memory= path > > > > ie. even vs. cache flush instructions (ie buffers in the memory > > > > controllers can still be out of sync). > > > >=20 > > > > Darwin does some gross hacks to work around that, some of them visi= ble > > > > in the AGP drivers, some burried in the Apple driver, I don't know = for > > > > sure. It's possible that they end up mapping all AGP memory as cach= e > > > > inhibited, but we can't do that because of our linear mapping. > > >=20 > > > We are doing that though... > >=20 > > This reminded me, I've been running with the patch below, but I'm not > > sure it makes any difference. Maybe Andreas or Jordan can try it. >=20 > It certainly is something we need to do, provided we also know there > will be no subsequent access to that page via a cachable mapping until > it's removed from AGP. TTM should take care of that. --=20 Earthling Michel D=C3=A4nzer | http://www.amd.c= om Libre software enthusiast | Debian, X and DRI developer