[PATCH 0/3] ARM: Meson6: enable SMP

[Maxime Ripard]

On Thu, Oct 02, 2014 at 05:26:53PM +0200, Arnd Bergmann wrote:
> On Thursday 02 October 2014 16:54:26 Maxime Ripard wrote:
> > On Thu, Oct 02, 2014 at 04:44:20PM +0200, Arnd Bergmann wrote:
> > > On Tuesday 30 September 2014 22:45:38 Carlo Caione wrote:
> > > > On mar, set 30, 2014 at 12:22:21 +0200, Arnd Bergmann wrote:
> > > > > On Tuesday 30 September 2014 10:46:46 Carlo Caione wrote:
> > > > > > On mar, set 30, 2014 at 10:43:52 +0200, Carlo Caione wrote:
> > > > > > > Amlogic Meson6 is a dual-core Cortex-A9. This patchset adds all the necessary
> > > > > > > pieces to boot the secondary CPU.
> > > > > > 
> > > > > > Sorry for the double sending.
> > > > > > Forgot to CC LAKML.
> > > > > 
> > > > > Looks good to me in principle, but I wonder about the CPU enable method.
> > > > > Are you able to implement PSCI in u-boot like it was done for allwinner?
> > > > > 
> > > > > This is mostly a question of whether the system comes up in secure mode
> > > > > or non-secure mode.
> > > > 
> > > > I would be able if I had the u-boot source code or the possibility to
> > > > flash the board I'm using. Unfortunately at this moment I don't have
> > > > either. Probably in the near future I'll be able to implement PSCI in
> > > > u-boot since Amlogic is kindly starting to provide documentation but now
> > > > this is the best I can do.
> > > 
> > > Ok, I see. Let's give Amlogic some more time then. I think it's better
> > > to merge other parts of the platform first when we can reasonably assume
> > > that we don't have to change the binding any more.
> > > 
> > > It would be a shame to merge this now and then make it obsolete by
> > > implementing PSCI but still having to carry around the original code
> > > for compatibility reasons.
> > 
> > More likely, PSCI is not going to be supported by the bootloaders of
> > the devices already in the wild, so we still have to provide them an
> > option. And even when it will, you'll still have to support both the
> > devices with the old bootloaders, and the one with the new.
> 
> It depends on how common the old boot loaders are, and whether it's
> possible to upgrade them. If we can get to the point where you can
> boot a kernel with a single CPU and have an easy way to update the
> boot loader, we don't need to support it.

I thought I heard Olof at some point ranting about this kind of
requirements, but ok :)

Still, holding off until something that hypothetical happens looks a
bit odd, doesn't it?

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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