matroxfb - wrong PLL calculation for Mystique and Mystique 220

Hello,
there is a long-standing problem in matroxfb (and also with xf86-video-mga) with PLL values calculation. It results in "wavy" vertical lines at least on Mystique and Mystique 220, especially where dotted horizontal lines are displayed.

On non-220 Mystique in 1024x768@85Hz, matroxfb calculates:
m=0x0f, n=0x69, p=0x00 (producing wavy vertical lines)

Windows driver calculates:
m=0x03, n=0x34, p=0x01 (producing straight vertical lines)

The resulting f_vco from windows values is 189713.5, which is above max_freq for this card. So it looks like the assumption that f_vco must be less or equal to max_freq is wrong. Could someone with access to MGA1064/1164 documentation look into this?

xf86-video-mga bug (with photos of the screen):
http://bugs.xfree86.org/show_bug.cgi?id14

Ondrej Zary