From mboxrd@z Thu Jan 1 00:00:00 1970 From: Knut Petersen Subject: Re: [PATCH 1/1 2.6.15-rc4-git1] Fix switching to KD_TEXT Date: Sat, 10 Dec 2005 07:28:21 +0100 Message-ID: <439A7585.6050600@t-online.de> References: <4398B888.50005@t-online.de> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 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.sourceforge.net with esmtp (Exim 4.30) id 1EkyCj-0003Bt-L0 for linux-fbdev-devel@lists.sourceforge.net; Fri, 09 Dec 2005 22:27:33 -0800 Received: from mailout02.sul.t-online.com ([194.25.134.17]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1EkyCi-0002wl-39 for linux-fbdev-devel@lists.sourceforge.net; Fri, 09 Dec 2005 22:27:33 -0800 In-Reply-To: <4398B888.50005@t-online.de> Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Knut Petersen Cc: linux-kernel@vger.kernel.org, linux-fbdev-devel@lists.sourceforge.net, Andrew Morton , "Antonino A. Daplas" Please do forget about that patch I sent to you some days ago. An enhanced version will follow soon. cu, knut Knut Petersen schrieb: > Every framebuffer driver relies on the assumption that the set_par() > function > of the driver is called before drawing functions and other functions > dependent > on the hardware state are executed. > > This assumption is false in two cases, and one is a genuine linux > bug: > > 1: Whenever you switch from X to a framebuffer console for the very > first time, there is a chance that a broken X system has _not_ set > the mode to KD_GRAPHICS, thus the vt and framebuffer code > executes a screen redraw and several other functions before a > set_par() is executed. This is believed to be not a bug of linux > but a bug of X/xdm. > > 2: Whenever a switch from X to a framebuffer console occures, > the pan_display() function of the driver is called once before > the set_par() function of the driver is called. Code path: > complete_change_console -> redraw_screen -> fbcon_switch -> > bit_update_start-> fb_pan_display -> xyz_pan_display. > This is clearly a bug of linux. > > Although our primary goal must be to fix linux bugs and not to work > around bugs of X, the patch fixes both of the cases. > > The advantage and correctness of this patch should be obvious. Yes, it > does add a possibly slow call to the fb_set_par() function, but at this > point it is necessary. > > Signed-off-by: Knut Petersen > > > diff -uprN -X linux/Documentation/dontdiff -x '*.bak' -x '*.ctx' > linuxorig/drivers/video/console/fbcon.c > linux/drivers/video/console/fbcon.c > --- linuxorig/drivers/video/console/fbcon.c 2005-12-02 > 12:18:04.000000000 +0100 > +++ linux/drivers/video/console/fbcon.c 2005-12-06 > 09:06:56.000000000 +0100 > @@ -2103,10 +2103,11 @@ static int fbcon_switch(struct vc_data * > fb_set_var(info, &var); > ops->var = info->var; > > - if (old_info != NULL && old_info != info) { > - if (info->fbops->fb_set_par) > - info->fbops->fb_set_par(info); > + if (old_info != NULL && old_info != info) > fbcon_del_cursor_timer(old_info); > + > + if (info->fbops->fb_set_par) { > + info->fbops->fb_set_par(info); > fbcon_add_cursor_timer(info); > } > > > ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click