Matrox DVI output - use BIOS?

[Ian Pilcher]

I just did my first Linux installation (Fedora Core 5) since I upgraded
my video hardware from G200/analog to G450/DVI.  Since Fedora Core 4
worked just fine with this hardware, I was surprised that I had a some-
what difficult time getting Fedora Core 5 set up.

It turns out that this hardware combination only works at the LCD's
native resolution, 1280x1024, when my virtual terminals are using a VESA
framebuffer of the same resolution (i.e. I boot with "vga=775").  Since
I've always booted Fedora Core 4 with this kernel option, I never saw a
problem.

I've done a little more experimentation, and discovered that resolutions
up to 1024x768 work if no VESA framebuffer is used.  If a VESA frame-
buffer is used, then the X resolution must match the framebuffer
resolution.  The most likely explanation for this phenomenon is that the
card's BIOS (which is presumably used by the VESA framebuffer code)
knows how to turn the DVI output on when switching modes.

I tested this by booting with a 640x480 framebuffer (vga=769) and
starting the X server at 1280x1024 with the vesa driver.  Sure enough, X
came up just fine.

This gave me an idea.  Could the mga driver use the VESA BIOS calls to
change video modes?

Note:  Non-working modes do not cause the X server to crash.  Instead my
       LCD displays "No Signal", "Signal Out Of Range", or a black
       screen.  I would guess that an analog display would work in these
       situations; unfortunately, I have misplaced the dongle required
       attach an analog display to this card.
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Ian Pilcher                                        i.pilcher at comcast.net
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