Re: 2.6.9-rc1: scrolling with tdfxfb 5 times slower

Paolo Ornati
2004-09-02T09:21:29Z

On Wednesday 01 September 2004 22:10, Antonino A. Daplas wrote:
> On Wednesday 01 September 2004 19:55, Paolo Ornati wrote:
> > > This patch sets info->var.yres_virtual to the maximum upon driver
> > > load. If this works, it's possible to get sub-1 second scrolling
> > > speed.
> > >
> > > Reverse the previous patch first, then apply this patch.
> >
> > Results for 2.6.9-rc1 + your patch (time cat MAINTAINERS):
> >
> > CONFIG_FB_3DFX_ACCEL=n
> > ~1.27 s
> >
> > CONFIG_FB_3DFX_ACCEL=y
> > ~0.18 s
> >
> > BUT with CONFIG_FB_3DFX_ACCEL enabled I get strange video
> > "corruptions" (like bitmaps with random colors) that go away simply
> > swithcing to another console and than back to the previous.
>
> Might be a clipping problem? Maybe we need to set an upper limit
> to vyres, don't know for sure.
>
> Try doing an fbset -vyres 800, then keep doubling the number until
> you get the artifacts. If possible, do it for other bpp.

Doing some tests I've discovered that BPP doesn't influence this behavior
(kernel 2.6.9-rc1 + your patch, CONFIG_FB_3DFX_ACCEL=y):

BPP 800 1600 3200 6400 <-- VYRES
8 OK OK OK X
16 OK OK OK X
24 OK OK OK X
32 OK OK OK X

The upper limit for VYRES (after a lot of tests) seems to be around
4100/4200 (with 4100 all seems OK while with 4200 there are some
corruptions). This is the same for all BPP.

I don't understand why I have this problem only with
CONFIG_FB_3DFX_ACCEL=y...

--
Paolo Ornati
Gentoo Linux (kernel 2.6.8-gentoo-r3)