From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Petr Vandrovec" Subject: Re: Comments on fbgen.c and fbcon-accel Date: Tue, 7 May 2002 15:33:02 +0200 Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <48088FD4B1B@vcnet.vc.cvut.cz> Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: Received: from zikova.cvut.cz ([147.32.235.100]) by usw-sf-list1.sourceforge.net with esmtp (Exim 3.31-VA-mm2 #1 (Debian)) id 17555y-0005Gh-00 for ; Tue, 07 May 2002 06:33:34 -0700 Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Id: List-Unsubscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: Antonino Daplas Cc: linux-fbdev-devel@lists.sourceforge.net On 7 May 02 at 21:26, Antonino Daplas wrote: > > And set_par() could do some optimizations based on a shadow map of the register > > contents, also to avoid artefacts when switching to a different VC with the > > same video timings. Like: > > > > write_reg(reg, val) > > { > > if (shadow[reg] != val) { > > shadow[reg] = val; > > hardware[reg] = val; > > } > > } I was doing that long ago in matroxfb, and it simple does not work :-( There is too many applications which programs video hardware directly. So currently matroxfb always reprogram most of registers, and for critical ones (PLL) it reads back value from hardware, and not from some shadow area. Speed difference is invisible and reliability is much better. Best regards, Petr Vandrovec vandrove@vc.cvut.cz _______________________________________________________________ Have big pipes? SourceForge.net is looking for download mirrors. We supply the hardware. You get the recognition. Email Us: bandwidth@sourceforge.net