Problems with ati driver on Tibook

[John R. Dunning]

    From: Alex Deucher <alexdeucher at gmail.com>
    Date: Mon, 4 Jan 2010 11:11:08 -0500
    
    
    I'm not sure if this sequence will cause any problems on PC laptops or
    not, I suppose it depends on the oem, so I've made the patch
    mac-specific for now.  If the attached patch works for you, I'll go
    ahead and commit it.
    
It seems to work so far.  I still have other issues with this machine,
but with one exception, I don't think they're due to this driver.

FWIW, the code I altered is a fairly direct crib from the radeon_fb
driver in the kernel.  See, for instance,
linux-2.6.31/src/drivers/video/aty.c, circa line 1020.  That's pretty
clearly doing the same sort of thing I patched in the xf86-video-ati
driver, even has similar comments about asic bugs.  That code is not
conditional. 

If you want to commit it, that's probably a step to the good.  I have
one other wacky thing that happens to the screen "every once in a
while", if I track that down and it turns out to be in this driver,
I'll send another patch.