From: njs@watson.ibm.com (Nick Simicich)
Subject: Re: X and a Trident8900C
Summary: I got those Trident monitor card blues.
Date: Thu, 12 Nov 1992 21:51:18 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM T.J. Watson Research Center

In article <1992Nov12.092417.22968@cs.kuleuven.ac.be> henkv@cs.kuleuven.ac.be (Henk Vandecasteele) writes:
>Hello to everybody,
>
>As it seems to be difficult to set up X on a Trident VGA -card I'm posting
>my Xconfig file.

I believe this to be true as well:  It is difficult to set up a Trident
SVGA card, but I have a theory.

I'm in the process of setting up a Trident as well, and I've gotten X to
work, well, a little.  I've not been successful in getting it to work in
any of the higher res modes, even though the board seems to have higher
specs than my CTX monitor.

I've tried a number of different configurations.  No matter what I do,
if I've specified 'chipset "tvga8900"', the monitor just darkens,
quietly. 

Also, If I attempt to do my own clock calculation with a fast on-card
clock (75 Mz, I know it is way too high) the monitor just darkens
quietly.

If, however, I don't specify a chipset, I can get X to run.  The monitor
clicks several times during X startup.  When X is shutdown, I have to
reboot to rccover.  (No matter what, when I start X, I have to reboot to
recover.  My command for starting X is "sync;startx".)  What I think is
happening is that:

The server is trying each chipset in turn, tvga8900 last because of the
order that it reports the support.

This is setting funky modes in the card, which is what is causing the
monitor to clatter.  The drivers aren't real careful about restoring the
modes properly between probes, so something is being set that needs to
be set.

X runs, but since the driver didn't make all of the changes, it has no
idea about what to unchange.  The reboot fixes it.  If I could figure
out what to do to cause the Trident Bios (version 3) to reset the card,
(other than rebooting) I would.  But the bios is not documented in the
user's manual, just a bunch of mode numbers for different geometries.

Environment:
    486/DX 33 Mz, Clone, AMI bios.
    IDE 200M Drive.
    Trident 8900C SVGA card, Trident BIOS 3.00, 1 meg video RAM on card.
    CTX Monitor (60 Mz video bandwidth, max horizontal scan rate 50 Mz,
                 Max refresh rate 90 Hz, cute little charts for sync 
                 timings.)
    SLS from about 3 days ago, recompiled to remove SCSI, math
        emulation, and to select mode 0 automatically on startup.
        All versions of software just as on SLS.  Ran mkfontdir in all
        font directories.

When X comes up, it comes up in a mode that looks pretty funky.  Using
Control-Alt-+ or Control-Alt--, I am able to cycle to a lesser mode,
which works, and looks better.  I believe that the higher mode is
overdriving my monitor's bandwidth.  The standard Trident PC/DOS Windows
drivers for those high resolutions work on my system, but cause a lot of
flicker, so I suspect that they use conservative bandwidth to pump the
monitor, and put up with the flicker.  Then again, maybe there is no way
to get those bandwiths out of the card no matter what the specs say.
You couldn't prove it by me.

Incidentally, I believe that part of the reason that X didn't come up
for me at one point in my testing was that the Mouse was set up
incorrectly.  The server was hanging on the open of a serial mouse on
the wrong port, methinks.  Specifying the mouse correctly helped.

Please don't get me wrong:  I am really impressed with this whole
system, and also with the SLS installation package.

Nick Simicich
Newsgroups: comp.os.linux