Messages in this thread |  | | Date | Sat, 10 Dec 2005 07:28:21 +0100 | From | Knut Petersen <> | Subject | Re: [PATCH 1/1 2.6.15-rc4-git1] Fix switching to KD_TEXT |
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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 <Knut_Petersen@t-online.de> > > > 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); > } > > >
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