Re: Error in fbcon_switch ?

[Geert Uytterhoeven <geert@linux-m68k.org>]

On Thu, 22 May 2008, Krzysztof Helt wrote:
> On Wed, 21 May 2008 09:17:45 +0200 (CEST)
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Tue, 20 May 2008, Krzysztof Helt wrote:
> 
> > > I found that root of the problem is that fbcon_switch copies the var.vmode 
> > > field from the previous console. If this copy is removed everything is alright, ie.
> > > 
> > > tty1 (lace) -> tty2 (non-lace) -> tty1 (lace) -> tty2 (non-lace)

I could easily reproduce it on my Amiga. Haven't tried on the PS3 yet.

Seems to be introduced by

commit e4fc27618b75234b721c4a13d0e0d9d07e75e641
Author: Antonino A. Daplas <adaplas@gmail.com>
Date:   Tue Nov 8 21:39:09 2005 -0800

    [PATCH] fbcon: Console Rotation - Prepare fbcon for console rotation

Strange I never noticed it before... Oh well, interlace doesn't seem to
be popular anymore.

> > > Is this a correct solution to the problem? What is a purpose of copying vmode field?
> > > 
> (...)
> > > IMO, at least the first three should not be copied. I am not sure about YWRAP and 
> > > CONUPDATE/SMOOTH_XPAN.
> > 
> > As it copies [xy]offset, it probably needs YWRAP/SMOOTH_XPAN/CONUPDATE.
> 
> As I thought more about it, the copy of [xy]offset is also wrong. What if I have
> one console with 4096 vyres and another with only 1024 vyres. Copying offsets
> between them does not make any sense. Setting offsets to zero makes more sense
> (there is no scrollback buffer available anyway).
> 
> > So I guess it should keep the bits under FB_VMODE_MASK.
> 
> Actually, the opposite. Bits under FB_VMODE_MASK should be cleared
> for old console, the remaining ones (YWRAP/SMOOTH_XPAN/CONUPDATE)
> can be copied (or-ed with new ones).

Sorry, that's what I meant (`keep' means do not copy).

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

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