[patch] VRAM detection in controlfb

[Tony Mantler]

At 2:09 AM -0500 6/4/2000, Michel Lanners wrote:
>Hi Franz,
>
>On   3 Jun, this message from Franz Sirl echoed through cyberspace:
>[hacking controlfb]
>> if you don't mind, would you try to replace the "dcbi" assembler
>>instructions
>> in the detection code with "dcbf" instructions? It seems Dan inherited
>>my bug
>> I had in the platinumfb driver...
>
>Sure, no problem.
>
>In what sense is that a bug, and what would be the symptom? I know close
>to nothing about PPC assembler, and fully understanding the detection
>code might help fix the detection problems we still have in some
>situations...

dcbi = data cache block invalidate. If you do this on a dirty cache block,
data will be lost.

dcbf = data cache block flush. If you do this on a block that isn't in a
coherent state, data will be lost.

If you have a block that's both dirty and incoherent... well, don't do that. :)


btw, my mail server messed up and I got bounced off the list a few weeks
back, have I missed anything interesting?


Cheers - Tony :)


--
Tony Mantler       Renaissance Nerd Extraordinaire     nicoya at apia.dhs.org
Winnipeg, Manitoba, Canada                     http://nicoya.feline.pp.se/


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