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From: Kevin Hilman <khilman@ti.com>
To: Colin Cross <ccross@android.com>
Cc: Len Brown <len.brown@intel.com>,
	linux-kernel@vger.kernel.org,
	Amit Kucheria <amit.kucheria@linaro.org>,
	linux-tegra@vger.kernel.org, linux-pm@lists.linux-foundation.org,
	linux-omap@vger.kernel.org,
	Arjan van de Ven <arjan@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [linux-pm] [PATCH 0/3] coupled cpuidle state support
Date: Wed, 14 Mar 2012 07:23:59 -0700	[thread overview]
Message-ID: <87mx7jjm68.fsf@ti.com> (raw)
In-Reply-To: <CAMbhsRRD2bdkcUZvScb-cF05e=R3h69bNVaTPFX4jBKBBOjuMg@mail.gmail.com> (Colin Cross's message of "Tue, 13 Mar 2012 17:47:20 -0700")

Colin Cross <ccross@android.com> writes:

> On Tue, Mar 13, 2012 at 5:28 PM, Colin Cross <ccross@android.com> wrote:
>> On Tue, Mar 13, 2012 at 4:52 PM, Kevin Hilman <khilman@ti.com> wrote:

[...]

>>>
>>> Checking the ready_count seemed like an easy way to do this, but did you
>>> have any other mechanisms in mind for CPUs to communicate that they've
>>> exited/aborted?
>>
>> Why not set a flag from CPU1 when it exits the low power state, and
>> have CPU0 spin on the powerdomain register or the flag?  You can then
>> use the parallel barrier function to ensure both cpus have seen the
>> flag and reset it to 0 before returning.
>
> I realized the parallel barrier helper was not included in the patch
> set I posted, it will be in the next patch set.  

Do you have an ETA for the next patchset?  I'll be glad to give it a
spin on OMAP4.

> Short version, no caller to cpuidle_coupled_parallel_barrier will
> return before all cpus in the coupled set have called it.  It allows
> you to resynchronize the cpus after an abort to ensure they have all
> seen the abort flag before clearing it and returning, leaving
> everything in the correct state for the next idle attempt.

OK, this sounds like it will work well for what I need.

Kevin

  reply	other threads:[~2012-03-14 14:23 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-21  0:09 [PATCH 0/3] coupled cpuidle state support Colin Cross
2011-12-21  0:09 ` [PATCH 1/3] cpuidle: refactor out cpuidle_enter_state Colin Cross
2012-01-04 14:08   ` [linux-pm] " Jean Pihet
2011-12-21  0:09 ` [PATCH 2/3] cpuidle: fix error handling in __cpuidle_register_device Colin Cross
2011-12-21  0:09 ` [PATCH 3/3] cpuidle: add support for states that affect multiple cpus Colin Cross
2011-12-21  9:02 ` [PATCH 0/3] coupled cpuidle state support Arjan van de Ven
2011-12-21  9:40   ` Colin Cross
2011-12-21  9:44     ` Arjan van de Ven
2011-12-21  9:55       ` Colin Cross
2011-12-21 12:12         ` Arjan van de Ven
2011-12-21 19:05           ` Colin Cross
2011-12-21 19:36             ` Arjan van de Ven
2011-12-21 19:42               ` [linux-pm] " Colin Cross
2011-12-22  8:35                 ` Shilimkar, Santosh
2011-12-22  8:53                   ` Arjan van de Ven
2011-12-22  9:30                     ` Shilimkar, Santosh
2011-12-22 21:20                     ` Colin Cross
2012-03-14  0:39           ` Colin Cross
2012-01-04  0:41 ` Kevin Hilman
2012-01-04 17:27   ` Shilimkar, Santosh
2012-01-20  8:46 ` Daniel Lezcano
2012-01-20 20:40   ` Colin Cross
2012-01-25 14:04     ` Daniel Lezcano
2012-01-31 14:13       ` Daniel Lezcano
2012-01-27  8:54     ` [linux-pm] " Vincent Guittot
2012-01-27 17:32       ` Colin Cross
2012-02-01 12:13         ` Vincent Guittot
2012-02-01 14:59           ` Lorenzo Pieralisi
2012-02-01 17:30             ` Colin Cross
2012-02-01 18:07               ` Lorenzo Pieralisi
2012-02-03  1:19                 ` Colin Cross
     [not found]   ` <8762e8kqi6.fsf@ti.com>
2012-03-14  0:28     ` Colin Cross
2012-03-14  0:47       ` Colin Cross
2012-03-14 14:23         ` Kevin Hilman [this message]
2012-03-14  2:04     ` Arjan van de Ven
2012-03-14  2:21       ` Colin Cross

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