On Sat, Apr 18, 1998 at 12:12:11PM -0400, Michael R Zucca wrote:
> Ok folks. Here's a patch for Quadra intvid that should hopefully do
> the following:
> 
> 1. Fix the "shitfted" video problem some users get in X
> 2. Enable fast block copying to video ram
> 
> So if some kind soul with a Quadra could build a kernel with the
> diff I've included below and test it, I'd appreciate it.
> 
> To test it do two things:
> 1. Start X and make sure that works
> 2. Test if there's any speed up on video operations by doing the
>    following:
> 
>    - Boot with an unpatched kernel. Find a really big directory
>      and time an ls -l on the console (scrolling uses lots of
>      block operations)
>    - Boot with the patched kernel and do the same thing.
>    - Run any other graphical tests you can think of
>      (Compile and run some Mesa programs :-)
> 
>    Hopefully there will be an appreciable difference in speed.
>    
> One last note: This is *not* a newbie project! If you've never
> built a kernel before please wait until I get this into the
> regular source. It may not work so I need experienced and
> adventurous people to do this. If the patch works then I
> will do a send-pr with the patch and it will make it into
> the official -current sources.
> 

OK. I tried this on my LC475. The results are as follows:

The fast block copying doesn't work at all. The screen stops updating
properly after the code which enables this is executed - though the machine
otherwise still works fine. When this happens pixels stop changing from
white, though the few pixels which are not white (because of the 20 lines or
so of console text which were written before this) are will change color as
something writes to them. If I comment out the line which enables fast
copying to vram then the video works again.

The shifted video problem is fixed in 1024x768 and 640x480 but not in
832x624. In 1024x768 and 640x480 the problem was that the video was shifted
up by 10 or so lines. Your patch has fixed this. In 832x624 mode the video
was shifted up by a few lines and left by about 100 pixels (i.e it wrapped
around) - the shifting up has been fixed, but the video display still wraps
around by 100 or so pixels. These effects occur in all bit depths.

It's probable that these problems are caused by the fact that the 475 and
605 use a different video controller than the other quadras. They have a
combined memory and video controller called the 'MEMC Jr'. I think I've
read somewhere on an apple tech info page that it is supposed to be
compatable with the video controller in the other quadras, but I don't know
how compatable they mean...

I believe the 575 may use the same video chip, since it uses the same 7.1
system enabler as the 475 and 605, but that's just a guess.

	david

--

David Johnston
david@canopus.apana.org.au