From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antonino Daplas Subject: Re: Some questions Date: 12 Mar 2003 05:45:35 +0800 Sender: linux-fbdev-devel-admin@lists.sourceforge.net Message-ID: <1047419056.1100.26.camel@localhost.localdomain> References: <1047407816.1013.182.camel@localhost.localdomain> <3E6E4D9A.7060003@winischhofer.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Received: from pine.compass.com.ph ([202.70.96.37]) by sc8-sf-list1.sourceforge.net with smtp (Exim 3.31-VA-mm2 #1 (Debian)) id 18src1-0006SD-00 for ; Tue, 11 Mar 2003 13:48:41 -0800 In-Reply-To: <3E6E4D9A.7060003@winischhofer.net> 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: Thomas Winischhofer Cc: James Simmons , Geert Uytterhoeven , Linux Fbdev development list On Wed, 2003-03-12 at 04:56, Thomas Winischhofer wrote: > > > > The choices are: > > > > 1. refresh the registers at every switch - slowest but guarantees > > hardware state is always preserved > > Bad. Takes long time, especially on LCD displays which always need a > little delay for backlight and sync stability reasons. > > > 2. do not refresh unless var changed - fasted but can result in > > corruption/crash if registers were changed behind the back of fbdev > > I think one can rely on tidyness of applications changing the registers. > Like X does. Unfortunately, this is what we are trying to prevent. X assumes that the console is in text mode, so only registers that affect text mode are restored. Frequently, cursor registers and bitmaps, as an example, are not refreshed. There's probably more, ie accel engine, etc. Of course, X is not totally to blame, it's doing its best to restore the console back. It really depends on the X drivers, how complicated they are, how comprehensive are their restore routines, etc. > > 3. selective refresh - do not refresh if switching between "trusted" > > consoles, refresh if switching from "untrusted" consoles. I actually prefer #3, and I already have working code for this. We can also make this driver switchable (ie, drivers that are not affected by X can disable this, and only drivers that are affected such as the riva, aty, radeon, etc can turn this on). Tony ------------------------------------------------------- This SF.net email is sponsored by:Crypto Challenge is now open! Get cracking and register here for some mind boggling fun and the chance of winning an Apple iPod: http://ads.sourceforge.net/cgi-bin/redirect.pl?thaw0031en