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Date: Fri, 15 Jul 2016 16:10:26 +0200
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
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        Richard Purdie <rpurdie@rpsys.net>, linux-leds@vger.kernel.org,
        Pawel Moll <pawel.moll@arm.com>
Subject: Re: [patch V2 43/67] leds/trigger/cpu: Convert to hotplug state
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* Jacek Anaszewski | 2016-07-14 13:55:26 [+0200]:

>On 07/14/2016 01:33 PM, Thomas Gleixner wrote:
>>That does not explain WHY this needs to happen in the low level bringup phase
>>of the CPU with interrupts disabled and can't be done from the normal ONLINE
>>callbacks in thread context.
>
>It was before my time in kernel, so I can only suppose that it was
>the easiest way. Does it introduce some problems?

It was introduced by Pawel Moll in fba14ae8e924 ("ledtrig-cpu: Handle
CPU hot(un)plugging"). It does not introduce any problems but those
bring up / bring down levels are usually used by the core code. This
does not look like it needs to be done _that_ early or late during the
removal / addition of a CPU to the system.

Which means this looks like it could be moved to CPU_ONLINE /
CPU_DOWN_PREPARE which in turns means we could use dynamic IDs instead
of those hardcoded ones since the LED subsystem does not depend on other
components.

Sebastian