[U-Boot] commit "powerpc: Remove warm reset entry point" does not work on mpc83xx

[Wolfgang Denk]

Dear Joakim Tjernlund,

In message <OFBC383CCF.86B567D6-ONC12577C1.006A80D5-C12577C1.006AA773 at transmode.se> you wrote:
>
> > During normal use I thought that the reset entry point was always
> > 0xXXXXX100 and a warm reset would never occur.
> 
> I am not so sure about this. Perhaps the Freescale guys can set us 
> straight?

Originally U-Boot (well, PPCBoot, to be more precise) had this notion
of a "warm start", but I quickly learned that this makes little sense
in a boot loader. When we execute the "reset" command,. we usually
want to _really_ reset the system into operational mode, including
not only the CPU itself but also co-processors (which might be running
some form of microcode or DMA), external controllers (to stop them
from doing DMA or other data transfers), NOR flash (to make sure it is
in read mode so we can execute code from it), etc.

Whenever this was not possible (usually due to hardware design
"features") this almost always was experienced as a "bug in U-Boot"
because there were situations where the board could only be reset
through full power cycle.

My recommendation is: stop thinking of "warm boot"; either perform a
"reset" (and that be a real, hard reset of the CPU core and all
peripherals), or just continue to run ;-)

Best regards,

Wolfgang Denk

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