Re: [PATCH 1/8] ARM: SCU: Add common routines for secondary CPUbootup

[Russell King - ARM Linux]

On Thu, Dec 02, 2010 at 06:01:50PM +0000, Russell King - ARM Linux wrote:
> On Thu, Dec 02, 2010 at 05:38:24PM +0000, Russell King - ARM Linux wrote:
> > What if a platform, for what ever reason, wants to have 3 CPUs,
> > numbered 0, 2, 3 ?  That's the reason why the code which sets the
> > possible and present maps isn't in the ARM core code - Eg, we don't
> > know if a platform wants to keep CPU 1 in AMP mode to run some
> > special software on it.
> > 
> > I don't think it's worth it because I think trying to considate this
> > is going to cripple the code structure in the future.
> 
> I don't think this is particularly worth it either:

As Catalin has pointed out:

http://lists.arm.linux.org.uk/lurker/message/20101202.162840.5465758c.en.html

The SCU is part of the core, and if you consult the TRMs for the MPCore
devices, it is actually different in ARM11 MPCore vs Cortex-A9 MPCore.
Cortex-A15 doesn't have a MMIO addressable SCU at all.

So, this is about as far as I want to go with stripping out the common
code from the various platforms (this includes my previous SMP series):

http://lists.arm.linux.org.uk/lurker/message/20101203.200746.31424430.en.html

This results in a net reduction of 242 LOC, as shown in the following
diffstat:

 arch/arm/include/asm/hardirq.h            |   18 ++
 arch/arm/include/asm/mach/irq.h           |    2 +-
 arch/arm/include/asm/smp.h                |   17 +-
 arch/arm/include/asm/smp_mpidr.h          |   17 --
 arch/arm/kernel/entry-armv.S              |    2 +-
 arch/arm/kernel/fiq.c                     |    5 +-
 arch/arm/kernel/head.S                    |   39 +++--
 arch/arm/kernel/irq.c                     |   23 ++-
 arch/arm/kernel/smp.c                     |  243 ++++++++++++++++-------------
 arch/arm/mach-msm/include/mach/smp.h      |    4 +-
 arch/arm/mach-omap2/omap-hotplug.c        |   14 +--
 arch/arm/mach-omap2/omap-smp.c            |   66 ++------
 arch/arm/mach-realview/hotplug.c          |   18 +--
 arch/arm/mach-realview/include/mach/smp.h |    5 +-
 arch/arm/mach-realview/platsmp.c          |   95 +++---------
 arch/arm/mach-s5pv310/hotplug.c           |   18 +--
 arch/arm/mach-s5pv310/include/mach/smp.h  |    5 +-
 arch/arm/mach-s5pv310/platsmp.c           |   46 +-----
 arch/arm/mach-tegra/hotplug.c             |   18 +--
 arch/arm/mach-tegra/include/mach/smp.h    |   12 +--
 arch/arm/mach-tegra/platsmp.c             |   33 +---
 arch/arm/mach-ux500/hotplug.c             |   18 +--
 arch/arm/mach-ux500/include/mach/smp.h    |    5 +-
 arch/arm/mach-ux500/platsmp.c             |   57 ++-----
 arch/arm/mach-vexpress/include/mach/smp.h |    5 +-
 arch/arm/mach-vexpress/platsmp.c          |   54 ++-----
 arch/arm/plat-omap/include/plat/smp.h     |    5 +-
 27 files changed, 301 insertions(+), 543 deletions(-)

Can someone also explain why OMAP uses different file naming from everyone
else?  It's annoying as (eg) arch/arm/*/platsmp.c for editing the platform
SMP support files gets everyone except OMAP.
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