From: Lukasz Luba <lukasz.luba@arm.com>
To: Luis Gerhorst <linux-kernel@luisgerhorst.de>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org,
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Dietmar.Eggemann@arm.com, cw00.choi@samsung.com,
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sudeep.holla@arm.com, viresh.kumar@linaro.org, nm@ti.com,
sboyd@kernel.org, rui.zhang@intel.com,
amit.kucheria@verdurent.com, daniel.lezcano@linaro.org,
mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
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shawnguo@kernel.org, s.hauer@pengutronix.de, festevam@gmail.com,
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bjorn.andersson@linaro.org, robh@kernel.org,
matthias.bgg@gmail.com, steven.price@arm.com,
tomeu.vizoso@collabora.com, alyssa.rosenzweig@collabora.com,
airlied@linux.ie, daniel@ffwll.ch, liviu.dudau@arm.com,
lorenzo.pieralisi@arm.com, patrick.bellasi@matbug.net,
orjan.eide@arm.com, rdunlap@infradead.org, mka@chromium.org
Subject: Re: [PATCH v6 04/10] PM / EM: add support for other devices than CPUs in Energy Model
Date: Fri, 10 Apr 2020 12:34:56 +0100 [thread overview]
Message-ID: <56053904-0314-340e-fdaa-4a8f649d7b6f@arm.com> (raw)
In-Reply-To: <87ftdboaqr.fsf@luis-debian.luis-debian-domain>
On 4/10/20 12:12 PM, Luis Gerhorst wrote:
>
> Lukasz Luba writes:
>
>> +/**
>> + * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for
>> a device
>> + * @dev : Device for which the EM is registered
>> + *
>> + * Try to unregister the EM for the specified device (it checks current
>> + * reference counter). The EM for CPUs will not be freed.
>> + */
>> +void em_dev_unregister_perf_domain(struct device *dev)
>> +{
>> + struct em_device *em_dev, *tmp;
>> +
>> + if (IS_ERR_OR_NULL(dev))
>> + return;
>> +
>> + /* We don't support freeing CPU structures in hotplug */
>> + if (_is_cpu_device(dev)) {
>> + dev_dbg_once(dev, "EM: the structures are not going to be
>> removed\n");
>> + return;
>> + }
>> +
>> + mutex_lock(&em_pd_mutex);
>> +
>> + if (list_empty(&em_pd_dev_list)) {
>> + mutex_unlock(&em_pd_mutex);
>> + return;
>> + }
>> +
>> + list_for_each_entry_safe(em_dev, tmp, &em_pd_dev_list,
>> em_dev_list) {
>> + if (em_dev->dev == dev) {
>> + kref_put(&em_dev->kref, _em_release);
>> + break;
>> + }
>> + }
>> +
>> + mutex_unlock(&em_pd_mutex);
>> +}
>> +EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);
>
> Ok, so em_dev_unregister_perf_domain() does not support the CPU device
> and a subsequent em_register_perf_domain() will fail with EEXIST.
Correct. At the current mainline Energy Model we don't even have
em_unregister_perf_domain function. I had to introduce it in order
to support other devices which might have drivers loaded/unloaded
as modules.
>
> Is there a way to unregister/change the CPU's energy model during
> runtime without restarting the whole system?
Not for the CPU for now.
It is possible for other devices. When you have i.e. a module driver for
a device and in your code there is a (*active_power)(), then it is
possible to change EM by unloading/loading the module.
For the CPU we don't have this requirement for production code. I will
add you to CC list when something like this would pop-up for a
prototyping/experimentation code. We have been analyzing some options.
Regards,
Lukasz
next prev parent reply other threads:[~2020-04-10 11:35 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-10 8:42 [PATCH v6 00/10] Add support for devices in the Energy Model Lukasz Luba
2020-04-10 8:42 ` [PATCH v6 01/10] PM / EM: change naming convention from 'capacity' to 'performance' Lukasz Luba
2020-04-23 9:55 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 02/10] PM / EM: introduce em_dev_register_perf_domain function Lukasz Luba
2020-04-23 10:46 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 03/10] PM / EM: update callback structure and add device pointer Lukasz Luba
2020-04-23 13:22 ` Daniel Lezcano
2020-04-23 15:28 ` Lukasz Luba
2020-04-10 8:42 ` [PATCH v6 04/10] PM / EM: add support for other devices than CPUs in Energy Model Lukasz Luba
2020-04-10 11:12 ` Luis Gerhorst
2020-04-10 11:34 ` Lukasz Luba [this message]
2020-04-10 14:35 ` kbuild test robot
2020-04-23 15:12 ` Daniel Lezcano
2020-04-23 16:57 ` Lukasz Luba
2020-04-23 17:15 ` Daniel Lezcano
2020-04-23 17:19 ` Lukasz Luba
2020-04-10 8:42 ` [PATCH v6 05/10] PM / EM: remove em_register_perf_domain Lukasz Luba
2020-04-23 15:14 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 06/10] PM / EM: change name of em_pd_energy to em_cpu_energy Lukasz Luba
2020-04-23 15:28 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 07/10] Documentation: power: update Energy Model description Lukasz Luba
2020-04-23 16:07 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 08/10] OPP: refactor dev_pm_opp_of_register_em() and update related drivers Lukasz Luba
2020-04-23 16:47 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 09/10] thermal: devfreq_cooling: Refactor code and switch to use Energy Model Lukasz Luba
2020-04-23 17:57 ` Daniel Lezcano
2020-04-24 10:02 ` Lukasz Luba
2020-04-24 10:43 ` Daniel Lezcano
2020-04-10 8:42 ` [PATCH v6 10/10] drm/panfrost: Register devfreq cooling and attempt to add " Lukasz Luba
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