From mboxrd@z Thu Jan  1 00:00:00 1970
From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi)
Date: Thu, 6 Jun 2013 10:30:26 +0100
Subject: Cache issues in vexpress cpu shutdown (regression in 3.10)
In-Reply-To: <20130606092132.GB28479@arm.com>
References: <1370430551.3387.11.camel@linaro1.home>
 <20130605113912.GE18614@n2100.arm.linux.org.uk>
 <20130605120539.GC32505@e102568-lin.cambridge.arm.com>
 <20130605190853.GF18614@n2100.arm.linux.org.uk>
 <20130606092132.GB28479@arm.com>
Message-ID: <20130606093025.GC2650@e102568-lin.cambridge.arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, Jun 06, 2013 at 10:21:32AM +0100, Catalin Marinas wrote:
> On Wed, Jun 05, 2013 at 08:08:53PM +0100, Russell King - ARM Linux wrote:
> > On Wed, Jun 05, 2013 at 01:05:39PM +0100, Lorenzo Pieralisi wrote:
> > > There is an A9 errata (fixed in r1p0) whereby CLIDR[23:21] reads as 0
> > > where it should read as 3'b001, so basically flush_cache_louis is not
> > > flushing anything. If that's the problem, either we add a generic fix
> > > in v7 cache assembly or we just fix it in platform code (by calling
> > > flush_cache_all()), since there should not be many pre-r1p0 around.
> > > 
> > > Please let me know what you think.
> > 
> > If we're providing a flush_cache_louis() function, then it better do
> > what it says or be removed.  So the right solution is to fix the
> > function rather than working around it, because over time we'll only
> > add more calls to flush_cache_louis() and it'll become a stumbling
> > block.
> 
> I think at some point we should define this unification level in the DT,
> maybe together with the CPU topology. We use LoUIS because it seems to
> be the right thing on all the existing platforms but it's nothing in the
> architecture that says LoUIS is the right level of flushing for the
> CPU-local caches.

I definitely agree. For the time being, I am willing to patch the code
with an errata fix, waiting for the link between cache levels and
topology (and power domains) to get in the kernel.

Lorenzo