Re: [9fans] NeoMagic MagicGraph 128 (NM2070, 10c8/0001)

[Dave Eckhardt <davide+p9@cs.cmu.edu>]

Based on Jim's advice, I've been working on extending the neomagic
driver to support the primeval NM2070.  I've made a bunch of progress
but would appreciate some informed advice.

The good news so far is:
* kernel code restructured to deal with 2070's single PCI memory region
* timing problems specific to 2070 fixed by ramming undocumented constants
  into "shadow registers" the way XF86 does
* existing cursor code correctly draws and positions
* rio paints grey desktop background
* the BIOS battery-status icon paints & unpaints when requested

For the moment I disabled acceleration (by not filling in scr->fill or
scr->scroll) since the 2070 doesn't do that the same way as later chips.

Current bad news:
* there is a band of bad pixels near the bottom of the screen which looks
  sort of like a random-dot stereogram
* when I right-button to bring up the rio menu, parts of it appear scattered
  to the right and below the correct place (30-ish little scraps, each fairly
  recognizable).  When the menu pops down, the scattered parts are un-drawn
  and the desktop is gray again.

Does the latter look like any standard mistake to anybody, e.g., "you're
not really in linear mode", "there is a scanline padding problem", etc.?

Is it possible that the memory layout is weird in some way which requires
acceleration for the chip to work?  If that seems likely I can push on that
for a while.

Dave Eckhardt