MCLK=100 breaks PowerBook

[Benjamin Herrenschmidt]

The default mclk setting of 100MHz for the Rage LT-G breaks on my
PowerBook G3 Series (garbage on screen, accelerated X hangs). I added
mclk:83 to my command line and it works fine again (and, progress from
pre-4, I have no more snow in X when moving things around).

>atyfb: 3D RAGE LT PRO [0x4c47 rev 0x80] 4M SGRAM, 230 MHz PLL, 83 Mhz MCLK

the chip ID 0x4c47 should be set to 83 MHz by default, not 100.

Note that I made a typo the first time I tested and I used 88Mhz. it
works fine too.

MacOS ATI driver creates a strange property in the device tree. It's name
is "MCLK,XCLK" and the value is 00001a38 00001a38. Geert, those values
have any meaning to you ? If you tell me how to do, I could calc the MCLK
used by MacOS by peeking appropriate registers from MacsBug and we could
use this value for the kernel with this chipID.


-- 
           E-Mail: <mailto:bh40 at calva.net>
BenH.      Web   : <http://calvaweb.calvacom.fr/bh40/>




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