From: khilman@kernel•org (Kevin Hilman)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 9/9] ARM: smp: Add runtime PM support for CPU hotplug
Date: Fri, 14 Aug 2015 11:59:31 -0700 [thread overview]
Message-ID: <7hlhdditm4.fsf@deeprootsystems.com> (raw)
In-Reply-To: <20150812204326.GM52339@linaro.org> (Lina Iyer's message of "Wed, 12 Aug 2015 14:43:26 -0600")
Lina Iyer <lina.iyer@linaro•org> writes:
> On Wed, Aug 12 2015 at 14:28 -0600, Kevin Hilman wrote:
>>Lina Iyer <lina.iyer@linaro•org> writes:
>>
>>> Enable runtime PM for CPU devices. Do a runtime get of the CPU device
>>> when the CPU is hotplugged in and a runtime put of the CPU device when
>>> the CPU is hotplugged off. When all the CPUs in a domain are hotplugged
>>> off, the domain may also be powered off and cluster_pm_enter/exit()
>>> notifications are be sent out.
>>>
>>> Cc: Catalin Marinas <catalin.marinas@arm•com>
>>> Cc: Mark Rutland <mark.rutland@arm•com>
>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm•com>
>>> Signed-off-by: Lina Iyer <lina.iyer@linaro•org>
>>
>>How does the runtiem PM usage with hotplug work with the runtime PM
>>usage in idle?
>>
>>IIUC, when a CPU is hotplugged in, it will always have a usecount of at
>>least 1, right? and if it's not idle, it will have done a _get() so it
>>will have a usecount of at least 2. So I'm not quite seeing how the
>>usecount will ever go to zero in idle and allow the domain to power_off.
>>
> When the CPU is online and running, it would have a ref count of 1. Then
> cpuidle would do a _put and the ref count would go to 0 and when coming
> out of idle, cpuidle would get a _get and the ref count will be back at
> 1. Ref count is not incremented when cpuidle is initialized on the CPU.
> So whenever the CPU is running, it would have a ref count of 1.
Ah, OK, that was the part I was missing.
Thanks,
Kevin
next prev parent reply other threads:[~2015-08-14 18:59 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-04 23:35 [PATCH 0/9] ARM: PM / Domains: Generic PM domains for CPUs/Clusters Lina Iyer
2015-08-04 23:35 ` [PATCH 1/9] PM / Domains: Allocate memory outside domain locks Lina Iyer
2015-08-12 19:47 ` Kevin Hilman
2015-09-01 12:40 ` Ulf Hansson
2015-08-04 23:35 ` [PATCH 2/9] PM / Domains: Remove dev->driver check for runtime PM Lina Iyer
2015-08-12 19:50 ` Kevin Hilman
2015-08-13 8:57 ` Geert Uytterhoeven
2015-08-14 3:40 ` Kevin Hilman
2015-08-14 7:24 ` Geert Uytterhoeven
2015-08-14 17:19 ` Kevin Hilman
2015-08-16 9:24 ` Geert Uytterhoeven
2015-08-21 21:04 ` Kevin Hilman
2015-08-24 19:50 ` Lina Iyer
2015-08-25 9:24 ` Geert Uytterhoeven
2015-09-01 13:28 ` Ulf Hansson
2015-08-04 23:35 ` [PATCH 3/9] PM / Domains: Support IRQ safe PM domains Lina Iyer
2015-08-12 20:12 ` Kevin Hilman
2015-08-12 20:47 ` Lina Iyer
2015-08-12 23:03 ` Stephen Boyd
2015-08-04 23:35 ` [PATCH 4/9] kernel/cpu_pm: fix cpu_cluster_pm_exit comment Lina Iyer
2015-08-12 20:13 ` Kevin Hilman
2015-08-04 23:35 ` [PATCH 5/9] ARM: common: Introduce PM domains for CPUs/clusters Lina Iyer
2015-08-06 3:14 ` Rob Herring
2015-08-07 23:45 ` Kevin Hilman
2015-08-11 13:07 ` Geert Uytterhoeven
2015-08-11 15:58 ` Lina Iyer
2015-08-11 20:12 ` Rob Herring
2015-08-11 22:29 ` Lina Iyer
2015-08-12 19:00 ` [PATCH v2 1/2] " Lina Iyer
2015-08-12 19:00 ` [PATCH v2 2/2] ARM: domain: Add platform handlers for CPU PM domains Lina Iyer
2015-08-13 17:29 ` [PATCH v2 1/2] ARM: common: Introduce PM domains for CPUs/clusters Rob Herring
2015-08-13 20:12 ` Lina Iyer
2015-08-13 22:01 ` Rob Herring
2015-08-14 14:38 ` Lina Iyer
2015-08-13 15:01 ` [PATCH 5/9] " Lorenzo Pieralisi
2015-08-13 15:45 ` Lina Iyer
2015-08-13 15:52 ` Lorenzo Pieralisi
2015-08-13 16:22 ` Lina Iyer
2015-08-14 3:51 ` Kevin Hilman
2015-08-14 4:02 ` Lina Iyer
2015-08-14 15:49 ` Lorenzo Pieralisi
2015-08-14 19:11 ` Kevin Hilman
2015-08-13 17:26 ` Sudeep Holla
2015-08-13 19:27 ` Lina Iyer
2015-08-14 9:52 ` Sudeep Holla
2015-08-04 23:35 ` [PATCH 6/9] ARM: domain: Add platform handlers for CPU PM domains Lina Iyer
2015-08-05 14:45 ` Rob Herring
2015-08-05 16:38 ` Lina Iyer
2015-08-05 19:23 ` Lina Iyer
2015-08-06 3:01 ` Rob Herring
2015-08-10 15:36 ` Lina Iyer
2015-08-04 23:35 ` [PATCH 7/9] ARM: cpuidle: Add runtime PM support for CPU idle Lina Iyer
2015-08-04 23:35 ` [PATCH 8/9] ARM64: smp: Add runtime PM support for CPU hotplug Lina Iyer
2015-08-04 23:35 ` [PATCH 9/9] ARM: " Lina Iyer
2015-08-12 20:28 ` Kevin Hilman
2015-08-12 20:43 ` Lina Iyer
2015-08-14 18:59 ` Kevin Hilman [this message]
2015-08-12 23:47 ` Stephen Boyd
2015-08-13 16:00 ` Lina Iyer
2015-08-13 19:18 ` Stephen Boyd
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