L2 cache support for pxa16x

[gores@marvell.com (Siddarth Gore)]

On Thu, 2010-05-20 at 07:06 -0700, Eric Miao wrote:
> On Thu, May 20, 2010 at 6:17 PM, Siddarth Gore <gores@marvell.com> wrote:
> > On Wed, 2010-05-12 at 03:11 -0700, Eric Miao wrote:
> >> On Wed, May 12, 2010 at 11:56 AM, Siddarth Gore <gores@marvell.com> wrote:
> >> > Hi Eric/Haojian,
> >> >
> >> > Can the Tauros2 support be used for pxa168 as well? The one difference I
> >> > can see is that L2 Enable is in control register instead of extra
> >> > feature register. But rest of the things look very similar to me.
> >> >
> >
> > I tried doing this. It works when I enable L2 before turning the MMU on,
> > i.e. in __mohawk_setup
> >
> > But when I do the following in tauros2_init(), the kernel crashes.
> > 1. flush and disable dcache
> > 2. invalidate and disable icache
> > 3. drain write buffer
> > 4. invalidate TLB
> > 5. invalidate L2
> > 6. enable L2
> > 7. enable icache
> > 8. enable dcache
> >
> > I think the right place to enable L2 is in tauros2_init, so any idea
> > what I am doing wrong here?
> >
> 
> I believe that was the reason why I didn't put tauros2 support to pxa168
> at the first place. And enabling L2 after MMU is enabled is supposed to
> be unsafe, which is mentioned in xscale3 manual, though not sure if that's
> the case for pxa168 as well.
> 
I did not find it mentioned anywhere in the mohawk (PJ1) datasheet. Also
any idea why is this unsafe? I clean and disable the L1 cache first so
all the page tables, etc. will be backed up in main memory before
turning L2 on. plus invalidate the entire L2, so all the fetches will
first go to main memory.

other CPUs using tauros2 (also feroceon) turn L2 on after MMU, and they
work fine.

-siddarth
> > -siddarth
> >
> >