From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH 1/2] fb: add support for foreign endianness Date: Tue, 19 Feb 2008 11:35:53 +1100 Message-ID: <1203381353.6740.59.camel@pasglop> References: <20080205154432.GA8749@localhost.localdomain> <20080214224942.a0cb6218.akpm@linux-foundation.org> <20080215164542.GB16810@localhost.localdomain> <20080218081847.e9e65f2f.krzysztof.h1@poczta.fm> <19805.1203355811@turing-police.cc.vt.edu> <47BA162C.5000807@anagramm.de> Reply-To: benh@kernel.crashing.org, linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1JRGTT-0007EY-PW for linux-fbdev-devel@lists.sourceforge.net; Mon, 18 Feb 2008 16:36:43 -0800 Received: from gate.crashing.org ([63.228.1.57] ident=[U2FsdGVkX1+xLU/FxLkccV544kWkfSX4wP+SgjBR2Ug=]) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1JRGTS-0001aO-AK for linux-fbdev-devel@lists.sourceforge.net; Mon, 18 Feb 2008 16:36:43 -0800 In-Reply-To: <47BA162C.5000807@anagramm.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-fbdev-devel-bounces@lists.sourceforge.net Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: Clemens Koller Cc: linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Geert Uytterhoeven , Andrew Morton On Tue, 2008-02-19 at 00:35 +0100, Clemens Koller wrote: > Valdis.Kletnieks@vt.edu schrieb: > > On Mon, 18 Feb 2008 08:18:47 +0100, Krzysztof Helt said: > >> I know two fb drivers which use endianess information (pm2fb and s3c2410fb). > >> Both resolve endianess at driver level. Actually, both handle it by setting special > >> bits so the graphics chip itself reorder bytes to transform foreign endianess. > >> I understand that this patch is for chips which cannot reorder bytes by themselves. > > > > Does anybody know of such a chip that's actually available in the wild? Or are > > we writing drivers for speculative possible chips? > > > > I had troubles with the Silicon Motion SM501/SM502 endianess on PowerPC PCI vs. LocalBus. > The chip also has a register to swap endianess, but that seems to only affect some > LocalBus modes. > The current fb and X drivers are working, but when it comes to font > aliasing and hw-acceleration, the problems start to rise again... Most "sane" gfx chips nowadays provide configurable surfaces that allow to perform the swap when writing/reading from regions of the framebuffer, with the ability to set a different swapper setting (based on bit depth) per region. Then there is also the risk that your PCI<->Localbus has been wired improperly :-) Ben. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/