From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 12 Dec 2002 02:39:41 +0000 (GMT) Received: from p508B7C81.dip.t-dialin.net ([80.139.124.129]:51111 "EHLO dea.linux-mips.net") by linux-mips.org with ESMTP id ; Thu, 12 Dec 2002 02:39:40 +0000 Received: (from ralf@localhost) by dea.linux-mips.net (8.11.6/8.11.6) id gBC2X7B29165; Thu, 12 Dec 2002 03:33:07 +0100 Date: Thu, 12 Dec 2002 03:33:07 +0100 From: Ralf Baechle To: Alan Cox Cc: Vivien Chappelier , linux-mips@linux-mips.org, Ilya Volynets Subject: Re: [PATCH 2.5] SGI O2 framebuffer driver Message-ID: <20021212033307.C22987@linux-mips.org> References: <1039656676.18587.63.camel@irongate.swansea.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <1039656676.18587.63.camel@irongate.swansea.linux.org.uk>; from alan@lxorguk.ukuu.org.uk on Thu, Dec 12, 2002 at 01:31:16AM +0000 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 876 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Thu, Dec 12, 2002 at 01:31:16AM +0000, Alan Cox wrote: > On Wed, 2002-12-11 at 23:41, Vivien Chappelier wrote: > > linear framebuffer (up to 8MB with 64kB granularity). I'm then remapping > > all those pages to one virtual region obtained from get_vm_area so that > > 1. caching attributes can be set to cacheable write-through no WA > > Ick. The framebuffer can't handle cached and write barriers ? The O2 is non-cache coherent. So with the fairly large write-back second level caches enabled frame buffer write could potencially be delayed indefinately but in any case quite long. Frame buffers are usually only written to, so the cache mode "uncached accelerated" seems preferable but only the R10000 provides this mode, so for the R5000 write-though no write allocation is the next best solution. Ralf