[Bug 216123] ofwfb: r269278 broke booting on Power Mac G4

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=216123

--- Comment #8 from Tom Lane <tgl at sss.pgh.pa.us> ---
Created attachment 179069
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=179069&action=edit
Minimum part of reverting r269278 to get CURRENT to boot

I've not had any luck bringing a kernel debugger to bear, but I've experimented
with the r269278 patch some more, and I can report that the portions attached
to this comment are the minimum needed to make it work.  Without the
seemingly-superfluous OF_open call in ofwfb_initialize, it freezes during boot
in the way previously described.  If the set-depth method call isn't removed
from ofwfb_init, it boots but the screen display is completely messed up ---
looks like it has the wrong idea about the framebuffer stride.

I'm not sure what to make of this.  I do not understand the division of labor
between ofwfb_initialize and ofwfb_init, nor what the intended call sequence
is, but I sort of suspect that the actual call sequence is different from what
the code's author expected.

Obviously, this is still not a committable patch; the "extra" OF_open call
might be safe enough, but removing the set-depth call would presumably
represent a loss on better hardware.  But perhaps this will give somebody an
idea of what to pursue.

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