On Wed, 19 Nov 2008, Michael Schmitz wrote:
> > Fix panning on ARAnyM (Falcon emulation). Without this, `fbtest test011'
> > fails
> > (for a 320x200x8 display with virtual 640x400).
>
> Fails how, exactly?
It shows a corrupted display (bad line length) if xoffset & 15 != 0.
> > As the original code in 2.4.x was the same, I'm wondering:
> > o Is this a bug in the ARAnyM emulation?
> > o xpanstep is 1, but judging from the visual output on ARAnyM, it looks
> > like
> > it should be 16?
> >
> > Signed-off-by: Geert Uytterhoeven <[EMAIL PROTECTED]>
> > ---
> > drivers/video/atafb.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > --- a/drivers/video/atafb.c
> > +++ b/drivers/video/atafb.c
> > @@ -1697,8 +1697,10 @@ static int falcon_pan_display(struct fb_
> > }
> > par->hw.falcon.line_offset = bpp *
> > (info->var.xres_virtual - info->var.xres) / 16;
> > +#if 0
> > if (par->hw.falcon.xoffset)
> > par->hw.falcon.line_offset -= bpp;
> > +#endif;
>
> The way I understand this code is:
>
> If var->xoffset has the low order bits set (sub-word pixel offset)
> par->hw.falcon.xoffset takes care of that, and xoffset takes care of the
> rest.
> Since the partial word offset shifts the beginnig of the scan line into the
> first word, the offset to the next scan line (par->hw.falcon.line_offset) has
> to
> be shortened.
Sounds reasonable. But the shortening part doesn't work on ARAnyM, nor do
small panning increments. So it really smells like an ARAnyM bug.
> I am pretty sure the pan step can be one (see par->hw.falcon.xoffset).
>
> I'll test your patch as soon as I get fbtest to work (missing libgcc_s.so.2).
The alternative is to compile fbtest yourself (CVS module
FBdev/utlilities/fbtest from project linux-fbdev on sf.net).
I've been thinking of putting a git clone on kernel.org...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [EMAIL PROTECTED]
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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