From mboxrd@z Thu Jan 1 00:00:00 1970
From: daniel.lezcano@linaro.org (Daniel Lezcano)
Date: Tue, 23 Apr 2013 15:43:45 +0200
Subject: [V3 patch 06/19] cpuidle: make a single register function for all
In-Reply-To: <516FB35D.7000303@ti.com>
References: <1365770165-27096-1-git-send-email-daniel.lezcano@linaro.org>
<1365770165-27096-7-git-send-email-daniel.lezcano@linaro.org>
<516FB35D.7000303@ti.com>
Message-ID: <51769011.7030608@linaro.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org
On 04/18/2013 10:48 AM, Santosh Shilimkar wrote:
> On Friday 12 April 2013 06:05 PM, Daniel Lezcano wrote:
>> The usual scheme to initialize a cpuidle driver on a SMP is:
>>
>> cpuidle_register_driver(drv);
>> for_each_possible_cpu(cpu) {
>> device = &per_cpu(cpuidle_dev, cpu);
>> cpuidle_register_device(device);
>> }
>>
> Not exactly related to $subject patch but the driver should
> be registered after all devices has been registered to avoid
> devices start using the idle state data as soon as it is
> registered. In multi CPU system, this race can easily happen.
Could you elaborate what problems the system will be facing if a cpu
starts using the idle state data as soon as it is registered ?
Is there a bug related to this ?
> Current CPUIDLE core layer is also written with the assumption
> that driver will be registered first and then the devices which
> is not mandatory as per typical drive/device model.
Yes, that's true. The framework assumes cpuidle_register_driver is
called before cpuidle_register_device.
> May be you can fix that part while you are creating this common
> wrapper.
Personally, as that will modify the cpuidle core layer and the changes
are not obvious (because of the design of the code) I prefer to do that
in a separate patchset if it is worth to do it - if there is a bug
related to it, then there is no discussion, we have to do it :)
[ ... ]
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