[U-Boot] [PATCH 0/6] Add ARMv8 PSCI framework

[Tom Rini <trini@konsulko.com>]

On Wed, Sep 28, 2016 at 03:16:38PM +0800, Hongbo Zhang wrote:
> On Wed, Sep 28, 2016 at 1:23 AM, Tom Rini <trini@konsulko.com> wrote:
> > On Tue, Sep 27, 2016 at 05:29:00PM +0800, macro.wave.z at gmail.com wrote:
> >> From: Hongbo Zhang <hongbo.zhang@nxp.com>
> >>
> >> This patch set introduces ARMv8 PSCI framework, all the PSCI functions are
> >> implemented a default dummy one, it is up to each platform to implement their
> >> own specific ones.
> >>
> >> The first 1/6 patch is a prepare clean up for adding ARMv8 PSCI.
> >> Patches 2/6 to 5/6 introduce new ARMv8 framework and set it up.
> >> The last 6/6 adds a most simple implementation on NXP LS1043 platform, to
> >> verify this framework.
> >>
> >> This patch set mainly introduces ARMv8 PSCI framework, for easier review and
> >> merge, further PSCI implementation on LS1043 is coming later.
> >>
> >> Hongbo Zhang (6):
> >>   ARMv8: LS1043A: change macro CONFIG_ARMV8_PSCI definition
> >>   ARMv8: Add secure sections for PSCI text and data
> >>   ARMv8: Add basic PSCI framework
> >>   ARMv8: Setup PSCI memory and dt
> >>   ARMv8: Enable SMC instruction
> >>   ARMv8: LS1043A: Enable LS1043A default PSCI support
> >
> > Conceptually this is good.  I have some issues around order of the
> > patches, and where the Kconfig entries end up.  Looking over the series
> > we introduce usage of some CONFIG symbols prior to declaring them in
> > Kconfig.  This is more of a hard no now as it will break bisecting when
> > the test for no new CONFIG symbols is tripped.  The other problem is
> > that I think the symbols you're adding in
> > board/freescale/ls1043ardb/Kconfig need to be in
> > arch/arm/cpu/armv8/Kconfig and then use default ... if ... to give the
> > right address for the layerscape boards.
> 
> Thanks Tom for quick response.
> 
> For config options introduced:
> CONFIG_ARMV8_PSCI
> CONFIG_ARMV8_PSCI_NR_CPUS
> CONFIG_CPU_PER_CLUSTER
> CONFIG_ARMV8_SECURE_BASE
> 
> I've tested adding patch one by one, there is no problem with the
> check-config script.

OK.

> And my idea was like this: let the CONFIG_ARMV8_PSCI to be an overall
> switch, and if it is enabled even without the other three ones, the
> default PSCI still works, as I've tested, this really works because
> any of the other three macros, when used, there is a #ifdef to check
> if it exists, if no, a default value is used or it isn't used at all.
> The later three macros, because they are platform specific so I
> intended to let every platform to define them.
> 
> This is slightly different from ARMv7, plan was if this get accepted,
> I would like to send patch to update ARMv7's.

I think that at the end of the day we need to have less options be
defined and asked under board/ and make more and in some cases better
use of the common Kconfig files.  Looking at how things are done in the
Linux Kernel, in general, can be instructive here.  Maybe the right
answer here is to have CONFIG_ARCH_WANT_GENERIC_PSCI_... with default y
(if most cases would be the generic one) and in the negative use the
other option which is board specific values.

But re-reading patch 6/6, I'm still not convinced that we shouldn't
start out with these being all in arch/arm/cpu/armv8/Kconfig, under the
PSCI option, for everyone, and default ... if layerscape.  And that
reminds that I wonder if we shouldn't have some higher level option to
say "I am ARMv8 Layerscape" to cover the cases where today we test vs a
number of TARGET_LS.... choices.  Thanks!

-- 
Tom
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