Re: [PATCH] arm: remove unused code in delay.S

From: Jamie Lokier
Date: Thu Sep 17 2009 - 15:33:14 EST


Russell King - ARM Linux wrote:
> On Tue, Sep 15, 2009 at 11:04:37PM +0200, Krzysztof Halasa wrote:
> > Steve Chen <schen@xxxxxxxxxx> writes:
> >
> > > +config OLD_CPU_DELAY
> > > + depends on CPU_32v3 || CPU_32v4 || CPU_32v4T
> > > + bool "Accurate delays"
> > > + def_bool n
> > > + help
> > > + Enable if observing longer than expected delays and need more
> > > + accuracy. This only applies to older CPUs.
> > > +
> >
> > If it's that simple then why not enable the extra delay code
> > unconditionally when compiling for those CPUs?
>
> Because it's really not that clear cut. Eg, ARM610 and ARM710 work
> better with it, but StrongARM suffers from delays being too short.
> Having a kernel configured for all those processors used to be common
> (since the Acorn RiscPC had pluggable CPU cards, which could be one
> of those processors.)
>
> It's really something that only experienced people should worry
> about, and not Joe "kernel-builder" Bloggs.

I'm confused now. If I'm building a "generic" kernel to run on
several different systems, including some ARM710s and some StrongARMs,
do I include the code or not?

Btw, do you know where PT110 fits in? Is it like StrongARM (SA110)?

Thanks,
-- Jamie

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