From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Fri, 3 Oct 2014 09:09:13 +0200 Subject: [PATCH 0/3] ARM: Meson6: enable SMP In-Reply-To: <1867489.B8srtuItsD@wuerfel> References: <1412066635-5298-1-git-send-email-carlo@caione.org> <3274534.jCjlMt5HJV@wuerfel> <20141002153804.GF4039@lukather> <1867489.B8srtuItsD@wuerfel> Message-ID: <20141003070913.GH4039@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Oct 02, 2014 at 05:50:35PM +0200, Arnd Bergmann wrote: > On Thursday 02 October 2014 17:38:04 Maxime Ripard wrote: > > 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? > > I was mainly trying to follow what you are doing in mach-sunxi, but maybe > I misunderstood what your plans are for PSCI support there. Well, we did it only for the A20, because: - We had a very good bootloader support already - And we needed it to be able to use it for virtualization AFAIK, the amlogic guys don't have such a bootloader yet, and can't use the virtualization, since it's a cortex-a9. Note that for all the other SoCs, where we don't have such a bootloader support, we do have smp_ops, or will have, because we can just use Allwinner's bootloader. > mach-meson is still in a very early stage, and it's not like SMP support > is the most important feature missing from it. If there are good reasons > to include the current patches in 3.19, we can do that. That's more of a mainlining scheduling discussion, and I can't really argue with that. I wouldn't have done it in that order, but I'm not really sure we can do that on that argument alone. The only question that should matter I guess is whether this feature improves the overall support of the SoC, and whether the code is clean enough. If both answers are yes, then I think it should come in. Remember that Carlo is a hobbyist, and doesn't really have an agenda :) Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: