linux-kernel - Re: [PATCH v2] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable

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Date:	Sat, 14 Feb 2015 10:01:22 +0000
From:	Magnus Damm <magnus.damm@...il.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Stephen Boyd <sboyd@...eaurora.org>,
	Simon Horman <horms@...ge.net.au>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Mark Rutland <mark.rutland@....com>,
	Nicolas Pitre <nico@...aro.org>,
	Dave Martin <Dave.Martin@....com>,
	SH-Linux <linux-sh@...r.kernel.org>
Subject: Re: [PATCH v2] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable

Hi Russell,

On Fri, Feb 13, 2015 at 11:01 PM, Russell King - ARM Linux
<linux@....linux.org.uk> wrote:
> On Fri, Feb 13, 2015 at 09:44:50PM +0000, Magnus Damm wrote:
>> Also, based on the comment in mcpm_cpu_can_disable() it looks like the
>> PSCI hook may be executed once only with your change in place?
>> Hopefully PSCI is OK not being invoked for every CPU shutdown.
>
> This is why I've said (in the parent thread) that I'm not happy to
> apply this patch.  Mark Rutland has indicated that he has MCPM cases
> where the CPUs which can be disabled changes dynamically according
> to the secure firmware requirements, and ripping out todays
> infrastructure in light of that, only to have to add it back again
> later makes no sense.
>
> However, cleaning things up by removing unnecessary cpu_disable
> methods is a good thing to do irrespective of that.

I completely agree!

Cheers,

/ magnus
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