[PATCH V2 1/5] arm: mvebu: Added support for coherency fabric in mach-mvebu

On 11/16/2012 07:56 PM, Will Deacon wrote:

On Thu, Nov 15, 2012 at 04:49:17PM +0000, Gregory CLEMENT wrote:

quoted

On 11/15/2012 05:21 PM, Will Deacon wrote:

quoted

Anyway, that's by-the-by as this is all called early enough that we
shouldn't care. The thing I don't like now is that the fabric initialisation
is done entirely differently on the primary CPU than the secondaries. The
primary probes the device-tree (well, it's also now hard-coded for v2) and
accesses the registers from a C function(armada_370_xp_set_cpu_coherent) whilst
the secondaries have hardcoded addresses and access via asm
(armada_xp_secondary_startup).

Now it is hardcoded in both case as you pointed it. So the last
difference is setup from a C function or via asm.

The differences between primary and secondary CPU when they enable the
coherency, is due to the fact that we really are in a different
situation. For primary CPU, as it is the only CPU online it doesn't
need to enable the coherency from the beginning, so we can wait to
have MMU enable and convenient feature. Whereas for the secondary CPU
they need the coherency from the very beginning are by definition they
won't be alone. That's why this very first instruction are written in
asm and they use physical address.

I don't see how to handle it in a different way.

The code paths are fine, I would just like to see less duplication. Can you
make the asm function PCS compliant and call it from C for the primary
(setting the link register to secondary_startup for the secondary cores)?

Have you a pointer on how to do it (make the asm function PCS compliant)?

I will also need to add a parameter, because the base address are not the
same between primary CPU and secondary CPUS. With the first we use virtual
address whereas with the second the physical address.

Will

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