radeonfb.c flakiness

[Benjamin Herrenschmidt]

>Tried that no help.  I have now figured out that the only way to make the
>DFP startup properly is to zap the parameter ram (one chime's worth) and
>then it will actually startup.  If I don't do that and I have been running
>MacOSX then no matter what I do or try it does right after the yaboot
>prompt I see a flash and then everything stays blank.

that's strange, since a friend of mine is experiencing exactly the same
issue with a Rage M6 (radeon mobility) in a titanium powerbook, while I
never see it here. The only difference is that his has a little bit slower
CPU.

>Perhaps Mac OSX driver is writing something to nvram or is moving the
>memory mapping for the card's interfaces.  Either way without that single
>pram zap, the screen simply goes dead and stays dead.

I think it doesn't write anything but mode & backlight infos. Make sure
your problem isn't caused by the powerbook backlight code ;) I think the
way we currently fetch the backlight setting from pram is kinda broken.

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