[PATCH] powerpc: reduce number of WATCHDOG_RESET calls from flush_cache

[Wolfgang Denk]

Dear Rasmus,

In message <afea5640-9d95-bf92-316a-0d674a5129ce at prevas.dk> you wrote:
> On 04/06/2020 12.31, Stefan Roese wrote:
> > On 04.06.20 11:30, Rasmus Villemoes wrote:
> >> Calling WATCHDOG_RESET for each and every cache line is overkill.
> >>
> >> In our case, the kernel image is a little over 7MB, and the almost
> >> 500000 calls of WATCHDOG_RESET() adds about one second to the
> >> boottime.
> >>
> >> I very highly doubt there's any real hardware where flushing 64K
> >> from cache to memory takes more than a few milliseconds, so this
> >> should be completely safe. Since it reduces the number of

Maybe it is, maybe it is not.  I remember boards where the watchdog
trigger had to happen in pretty tight intervals, something like min
20, max 60 milliseconds.

> >> +        if ((addr & (SZ_64K - 1)) == 0)

In any case, please write readable code.  The use of SZ_ here is not
a good idea.  Also, you might want to make the actual parameter
configurable, so boards with specific timing requirements can adjust
this as needed.

Best regards,

Wolfgang Denk

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