[1/3] powerpc/powernv: define a standard delay for OPAL_BUSY type retry loops

[Michael Ellerman]

On Tue, 2018-04-10 at 11:49:31 UTC, Nicholas Piggin wrote:
> This is the start of an effort to tidy up and standardise all the
> delays. Existing loops have a range of delay/sleep periods from 1ms
> to 20ms, and some have no delay. They all loop forever except rtc,
> which times out after 10 retries, and that uses 10ms delays. So use
> 10ms as our standard delay. The OPAL maintainer agrees 10ms is a
> reasonable starting point.
> 
> The idea is to use the same recipe everywhere, once this is proven to
> work then it will be documented as an OPAL API standard. Then both
> firmware and OS can agree, and if a particular call needs something
> else, then that can be documented with reasoning.
> 
> This is not the end-all of this effort, it's just a relatively easy
> change that fixes some existing high latency delays. There should be
> provision for standardising timeouts and/or interruptible loops where
> possible, so non-fatal firmware errors don't cause hangs.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/34dd25de9fe3f60bfdb31b473bf04b

cheers