Subject: Fixes for TGA driver in XFree86
To: None <>
From: Michael Kukat <>
List: port-alpha
Date: 11/26/2004 08:48:39

okay, i started fiddling around now. Current first improvement in the tga
driver in XFree86 (tested on NetBSD/alpha 2.0RC4):

For now, a table of modes for the selections of the rotary switch existed in
some strange order, with parts enabled/disabled by defines. As the programming
of the clock chip doesn't seem to be really known, this table with known
settings is scanned according to the resulting modeline. This scan just checks
for V/H resolution, and due to the nature of this scan funktion and the table,
any 1280x1024 mode results in 72Hz VSync selection. This is suboptimal on
TFTs, which are better used with 60Hz. Yesterday evening i completely
re-ordered this code, now the full mode table is available, and the scan
routine also uses the integer value of the pixel clock to find a matching
mode. The output now correctly finds mode 2, which is 1280x1024@60Hz and
matches the correct rotary switch setting 2. You now have to get a modeline
with correct V/H-resolution and correct pixel clock (at least the integer MHz
must match). Due to this should not really be a problem, the routine should be
a bit better now.

The next issue is the mentioned too bright picture on TFTs, i'll try to play
around with some RAMDAC registers and hopefully get this fixed by this.

If this really works, and if i find the time, i even would try to add working
support for the PowerStorm 4D20, which is 24bit, and currently "just" has
palette problems, but i didn't check further. Besides those evil color
problems, the card seems to work okay. And as all those TGAs are based on the
same chipset, i assume that fixing those DAC problems should enable using all
TGA models. I can just test with old TGA, 8bit TGA2 (PBXGB-AA) and 24bit TGA2

But now for the place to address these patches. First, does anyone use these
cards, maybe with TFTs and maybe having the same problems with too high black
levels? Meaning - is there any interest for improved TGA support?

And second... should the fixes flow in at XFree86 directly (where i have to
find out where to post them :), or can i just send a cvs diff for xsrc here
and someone has contact to the XFree86 team (Mel Kravitz did lots of works
here with NetBSD/alpha and xsrc) and can feed the diffs there?

Maybe in a later stage i'll try to get some cards running which are currently
not running. Matrox MilII support would be nice, as the cards are cheap and

Besides this: Mel, good work! You gave a base to check lots of cards on
different Miatas recently, where the results not yet went here i think.


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