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Re: [PATCH 0/3] MIPS: CMP: Add CPU hotplug support for CMP platforms.

To: "Steven J. Hill" <Steven.Hill@imgtec.com>
Subject: Re: [PATCH 0/3] MIPS: CMP: Add CPU hotplug support for CMP platforms.
From: Paul Burton <paul.burton@imgtec.com>
Date: Fri, 17 Jan 2014 16:34:50 +0000
Cc: <linux-mips@linux-mips.org>, <blogic@openwrt.org>
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On Fri, Jan 17, 2014 at 10:18:52AM -0600, Steven J. Hill wrote:
> From: "Steven J. Hill" <Steven.Hill@imgtec.com>
> 
> Add CPU hotplug support for cores with a CM.
> 
> Steven J. Hill (3):
>   MIPS: CMP: Add support for CPU hotplugging.
>   MIPS: CMP: Malta: Add support for CPU hotplugging.
>   MIPS: CMP: Malta: Enable CPU hotplug.
> 
>  arch/mips/Kconfig                |    1 +
>  arch/mips/include/asm/amon.h     |    1 +
>  arch/mips/include/asm/gcmpregs.h |    2 +
>  arch/mips/kernel/irq-gic.c       |    6 +-
>  arch/mips/kernel/smp-cmp.c       |  167 
> +++++++++++++++++++++++++++-----------
>  arch/mips/mti-malta/malta-amon.c |  107 ++++++++++++++++++++----
>  arch/mips/mti-malta/malta-int.c  |    2 +-
>  7 files changed, 216 insertions(+), 70 deletions(-)
> 
> -- 
> 1.7.10.4
> 
> 

No. As I've said internally a few times this is *not* what hotplug is
meant to be. This doesn't actually make use of the CM/CPC to power down
a core (and can't via the CMP framework/AMON interface). It is
ultimately pointless and in my opinion should be replaced by proper
hotplug (that actually powers down cores) built atop the CONFIG_MIPS_CPS
implementation (that already moves the BEV) which I submitted a few days
ago.

Paul


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