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SubjectRe: [PATCH] x86: GEODE: cache results from geode_has_vsa2() and uninline
On Tue, 29 Apr 2008 13:35:12 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Tue, 29 Apr 2008 01:32:13 -0400
> Andres Salomon <dilinger@queued.net> wrote:
>
> > On Mon, 28 Apr 2008 20:06:51 -0700
> > Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > > On Mon, 21 Apr 2008 17:02:30 -0400 Andres Salomon <dilinger@queued.net> wrote:
> > >
> > > > + if (!is_geode() || geode_has_vsa2())
> > >
> > > geode_has_vsa2() is a fairly expensive-looking function and afacit only
> > > needs to be evaluated once per boot. Perhaps we should cache it somewhere?
> > >
> >
> > How about this?
> >
>
> Looks sane. Although one wonders if it should be cached as one of the
> standard x86 feature bit thingies which show up in /proc/cpuinfo's 'flags'
> field.
>

The VSA lives in a weird place between hardware and BIOS. I'm not
really sure whether it's appropriate for it to be an x86_cap_flags (it
hadn't occurred to me), but I think of it more as BIOS. Jordan, what do
you think?



> > +static int has_vsa2 = -1;
> > +
> > +int geode_has_vsa2(void)
> > +{
> > + if (has_vsa2 == -1) {
> > + /*
> > + * The VSA has virtual registers that we can query for a
> > + * signature.
> > + */
> > + outw(VSA_VR_UNLOCK, VSA_VRC_INDEX);
> > + outw(VSA_VR_SIGNATURE, VSA_VRC_INDEX);
> > +
> > + has_vsa2 = (inw(VSA_VRC_DATA) == VSA_SIG);
> > + }
> > +
> > + return has_vsa2;
> > +}
> > +EXPORT_SYMBOL_GPL(geode_has_vsa2);
>
> nit:
>
> --- a/arch/x86/kernel/geode_32.c
> +++ a/arch/x86/kernel/geode_32.c
> @@ -161,10 +161,10 @@ void geode_gpio_setup_event(unsigned int
> }
> EXPORT_SYMBOL_GPL(geode_gpio_setup_event);
>
> -static int has_vsa2 = -1;
> -
> int geode_has_vsa2(void)
> {
> + static int has_vsa2 = -1;
> +

Looks good.

Acked-by: Andres Salomon <dilinger@debian.org>

> if (has_vsa2 == -1) {
> /*
> * The VSA has virtual registers that we can query for a
>




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