[PATCH v2] ARM64: kernel: implement ACPI parking protocol

Catalin Marinas catalin.marinas at arm.com
Wed Oct 7 06:03:47 PDT 2015

On Tue, Oct 06, 2015 at 06:31:52PM +0100, Lorenzo Pieralisi wrote:
> On Tue, Oct 06, 2015 at 01:15:32PM -0400, Mark Salter wrote:
> > On Tue, 2015-10-06 at 17:50 +0100, Catalin Marinas wrote:
> > > Question to Lorenzo and Mark Salter: was this patch successfully tested
> > > on real hardware (like Applied X-Gene)?
> > 
> > It doesn't work on X-Gene/Mustang because the existing firmware
> > implementations are not exactly compliant with the parking protocol
> > spec. I've been hacking on the firmware trying to get something
> > which will work wrt the spec but keep getting distracted by other
> > things.
> I tested the code on AMD Supercharger even though I had to change
> the remap implementation since the existing firmware uses cacheable
> mappings for the mailboxes.
> I put it together to make sure that it is there if any platform
> compliant with it relies on it and more importantly to prevent
> non-compliant implentations from trickling into the kernel,
> basically to prevent broken firmware implementations from being
> considered compliant and "working".

That's a good point. However, AFAIK, AMD are using PSCI already in their
firmware implementation and that's what we recommend anyway if EL3 is

So this patch is mainly aimed at X-Gene since other implementations I'm
aware of have EL3 already. What are the chances of Applied Micro fixing
their firmware and actually using this patch? (not a question for you;
I'm hoping some Applied engineers would comment).


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