linux-kernel - Re: [PATCH 0/3] cpuidle: updates related to tick_broadcast

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Date:	Wed, 13 May 2015 17:31:28 -0700
From:	Kevin Hilman <khilman@...nel.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	rlippert@...gle.com,
	"linux-pm\@vger.kernel.org" <linux-pm@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Sudeep Holla <sudeep.holla@....com>,
	linuxppc-dev@...ts.ozlabs.org, Lina Iyer <lina.iyer@...aro.org>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 0/3] cpuidle: updates related to tick_broadcast_enter() failures

"Rafael J. Wysocki" <rjw@...ysocki.net> writes:

> On Wednesday, May 13, 2015 05:13:27 PM Kevin Hilman wrote:
>> On Wed, May 13, 2015 at 5:16 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>> > On Wednesday, May 13, 2015 03:59:55 PM Kevin Hilman wrote:
>> >> "Rafael J. Wysocki" <rjw@...ysocki.net> writes:
>> >>
>> >> [...]
>> >>
>> >> > Second, quite honestly, I don't see a connection to genpd here.
>> >>
>> >> The connection with genpd is because the *reason* the timer was
>> >> shutdown/stopped is because it shares power with the CPU, which is why
>> >> the timer stops when the CPU hits ceratin low power states.  IOW, it's
>> >> in the same power domain as the CPU.
>> >
>> > Well, what if you don't have genpd on that system?  Is the problem at hand not
>> > relevant then magically?
>> 
>> Well, if you're not using genpd to model hardware power domain
>> dependencies, then yes you'll definitely need a different solution.
>> 
>> And, as we discussed on IRC.  If you only care about timers, and genpd
>> is not in use, then $SUBJECT series is a fine approach, and I have no
>> objections.  But for SoCs where there are several other things that
>> share power with CPU, we need a more generic, genpd based solution,
>> which it seems we're in agreement on.  And since the two approaches
>> are not mutually exclusive, then I have real objections to applying
>> this series.
>
> I guess a "no" is missing in the last sentence. ;-)

Correct.  I have *no* real objections to applying this series.

Kevin

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