[PATCH] ARM: MM: use 64bytes of L1 cache on plat S5PC1xx

[Marc Zyngier]

On Tue, 17 Nov 2009 10:15:49 +0100
Marek Szyprowski <m.szyprowski at samsung.com> wrote:

Hi Marek,

> Hello,
> 
> On Tuesday, November 17, 2009 9:10 AM Marc Zyngier wrote:
> 
> > On Tue, 17 Nov 2009 08:47:54 +0100
> > Marek Szyprowski <m.szyprowski at samsung.com> wrote:
> > 
> > > From: Kyungmin Park <kyungmin.park at samsung.com>
> > >
> > > Samsung S5PC1xx SoCs are Coretex8 based, so use 64 bytes of L1
> > > cache line instead of the default 32 bytes.
> > >
> > > Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> > > Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> > > ---
> > >  arch/arm/mm/Kconfig |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
> > > index 9264d81..7b7d4c3 100644
> > > --- a/arch/arm/mm/Kconfig
> > > +++ b/arch/arm/mm/Kconfig
> > > @@ -774,5 +774,5 @@ config CACHE_XSC3L2
> > >
> > >  config ARM_L1_CACHE_SHIFT
> > >  	int
> > > -	default 6 if ARCH_OMAP3
> > > +	default 6 if ARCH_OMAP3 || ARCH_S5PC1XX
> > >  	default 5
> > 
> > If this feature is related to the S5PC1xx being a CortexA8, why not
> > depend on CPU_V7 rather that adding each and every new CortexA8
> > implementation to this list?
> 
> There can be ARM v7 CPUs with different size of L1 line cache -
> Cortex-R4 is an example of such: 
> http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0363d/Caccifbd.html
> (32 bytes of L1 cache line size).
> 
> This config option should depend on particular ARM core
> implementation, otherwise it will be hard cover all possibilities.

Then what about introducing a CORTEX_A8 symbol, selected by ARCH_OMAP3,
ARCH_S5PC1XX and others to come, and that would select the right cache
line value? We really want to avoid those ever growing dependency lines
that lead to conflicts when applying patches from multiple sources.

Unless we can have a Cortex-A8 implementation with a cache line that is
not 64 bytes?

	M.
-- 
Fast. Cheap. Reliable. Pick two.