[RFC/Patch] 4xx idle loop

[Cort Dougan]

I can only think of three ifdef's that would be necessary now but it could
grow.  If the #ifdef snarl is unattractive in idle.c it's easy enough to
move it to chipfamily-specific headers so that idle.c just needs to call
arch_idle() to enter an idle state.

The function pointer isn't desirable.  What the correct strategy for power
saving is known at compile time so there shouldn't be a function pointer
dereference.  How the #ifdef's are done doesn't really matter as long as
the inefficiency of a function pointer is avoided.

} I thought one of the linuxppc desgin goals was to keep the ifdefs to a
} minimum.  I can see idle.c growing quite large and full of #ifdefs if we
} do it that way.  Rather than using ppc_md, make power_save an
} abstraction similar to platform_init.
}
} >
} >
} >} This sounds like a good idea if we could use
} >}   if( ppc_md.powersave != NULL)
} >}        ppc_md.powersave();
} >}
} >} If it is determined that calling power_save() which is resides in an
} >} arch/processor specific file then we are talking about many files being
} >} hit.  and the current power_save seems to common for many other ppc
} >} platforms other than 4xx & 8xx

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