lkml.org 
[lkml]   [2002]   [Dec]   [11]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [Linux-fbdev-devel] Re: atyfb in 2.5.51
FromAntonino Daplas <>
Date11 Dec 2002 17:49:35 +0500
On Wed, 2002-12-11 at 04:11, Benjamin Herrenschmidt wrote:
> 
> I don't know if happened with earlier fbdev versions for you, but one
> possibility is that X reconfigures the display base, and possibly more
> bits of the card's internal memory map. Either fbdev should restore
> that, or adapt to what X set. On R128's and radeon's, this is things
> like DISPLAY_BASE_ADDR.
> 
Although this is in the faqs for a long time, (behavior is undefined if
fbdev is used with software that touches the video card) this is an
issue that needs to be taken into consideration.  Without the set_var()
hook, fbcon will depend on the contents of info->var if there is a need
to touch the hardware or not.  And switching from X to the console will
not change the var, but since X actually did touch the hardware, you
just messed up your screen or worse, crashed the hardware.

Before, most drivers just unconditionally refresh the hardware at every
switch  during set_var(). I've been pointing this out for a long time
now, do we unconditionally do a check_var()/set_par() after every
console switch, or do we rely on fbdev and X cooperating with each
other? Or better, maybe fbcon has a way of knowing if the switch came
from  Xfree86.

Tony

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:31    [from the cache]
©2003-2008