lkml.org 
[lkml]   [2008]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] x86: GEODE: cache results from geode_has_vsa2() and uninline
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.

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


\
 
 \ /
  Last update: 2008-04-29 22:43    [W:0.169 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site