[PATCH v2] RFC: ARM: cache-l2x0: update workaround for PL310 errata 727915

[Will Deacon]

Hi Colin,

On Fri, May 25, 2012 at 09:04:22PM +0100, Colin Cross wrote:
> On Fri, May 25, 2012 at 7:56 AM, Will Deacon <will.deacon at arm.com> wrote:
> > Right, ok. This is definitely a different problem though. Firstly, r3p1 is
> > not affected by the original erratum and secondly the symptoms do not
> > include deadlock. The clean during boot also sounds highly suspicious -- is
> > there a chance you boot the kernel with a dirty L2? Is the L2 enabled or
> > disabled when entering the kernel [I think u8500 has it enabled]?
> 
> In a previous thread, I wrote that the 4430 I was using had r2p0.  I
> can't verify the accuracy of that claim right now, but my patch was
> based on that assumption.  Where are you getting r3p1 from?

Apologies, that's what Santosh mentioned here:

http://lists.infradead.org/pipermail/linux-arm-kernel/2012-May/101302.html

so, assuming that it's the same problem, it seems that both r3p1 and r2p0
are affected.

> When I said I couldn't reproduce the issue with clean during boot, I
> meant that I couldn't trigger the issue during boot by calling clean
> repeatedly.  I could still reproduce the issue after boot even if the
> cache was cleaned during boot.

Ok, that's interesting. I wonder if erratum #769419 is to blame? We now have
a workaround in the kernel for that, so you could give it a try if you're in
a position to do so.

Cheers,

Will