From: Lukasz Luba <lukasz.luba@arm.com>
To: Daniel Lezcano <daniel.lezcano@linaro.org>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
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Cc: Morten.Rasmussen@arm.com, Dietmar.Eggemann@arm.com,
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lorenzo.pieralisi@arm.com, patrick.bellasi@matbug.net,
orjan.eide@arm.com, rdunlap@infradead.org, mka@chromium.org
Subject: Re: [PATCH v5 1/5] PM / EM: add devices to Energy Model
Date: Mon, 6 Apr 2020 14:29:56 +0100 [thread overview]
Message-ID: <cb7f670a-a04f-ba6f-1486-0421f3cce2e9@arm.com> (raw)
In-Reply-To: <09b680a5-a118-8c6e-0ae1-03ab5f10c573@linaro.org>
Hi Daniel,
Thank you for the review.
On 4/3/20 5:05 PM, Daniel Lezcano wrote:
>
> Hi Lukasz,
>
>
> On 18/03/2020 12:45, Lukasz Luba wrote:
>> Add support of other devices into the Energy Model framework not only the
>> CPUs. Change the interface to be more unified which can handle other
>> devices as well.
>
> thanks for taking care of that. Overall I like the changes in this patch
> but it hard to review in details because the patch is too big :/
>
> Could you split this patch into smaller ones?
>
> eg. (at your convenience)
>
> - One patch renaming s/cap/perf/
>
> - One patch adding a new function:
>
> em_dev_register_perf_domain(struct device *dev,
> unsigned int nr_states,
> struct em_data_callback *cb);
>
> (+ EXPORT_SYMBOL_GPL)
>
> And em_register_perf_domain() using it.
>
> - One converting the em_register_perf_domain() user to
> em_dev_register_perf_domain
>
> - One adding the different new 'em' functions
>
> - And finally one removing em_register_perf_domain().
I agree and will do the split. I could also break the dependencies
for future easier merge.
>
>
>> Acked-by: Quentin Perret <qperret@google.com>
>> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
>> ---
>
> [ ... ]
>
>> 2. Core APIs
>> @@ -70,14 +72,16 @@ CONFIG_ENERGY_MODEL must be enabled to use the EM framework.
>> Drivers are expected to register performance domains into the EM framework by
>> calling the following API::
>>
>> - int em_register_perf_domain(cpumask_t *span, unsigned int nr_states,
>> - struct em_data_callback *cb);
>> + int em_register_perf_domain(struct device *dev, unsigned int nr_states,
>> + struct em_data_callback *cb, cpumask_t *cpus);
>
> Isn't possible to get rid of this cpumask by using
> cpufreq_cpu_get() which returns the cpufreq's policy and from their get
> the related cpus ?
We had similar thoughts with Quentin and I've checked this.
Unfortunately, if the policy is a 'new policy' [1] it gets
allocated and passed into cpufreq driver ->init(policy) [2].
Then that policy is set into per_cpu pointer for each related_cpu [3]:
for_each_cpu(j, policy->related_cpus)
per_cpu(cpufreq_cpu_data, j) = policy;
Thus, any calls of functions (i.e. cpufreq_cpu_get()) which try to
take this ptr before [3] won't work.
We are trying to register EM from cpufreq_driver->init(policy) and the
per_cpu policy is likely to be not populated at that phase.
Regards,
Lukasz
[1]
https://elixir.bootlin.com/linux/latest/source/drivers/cpufreq/cpufreq.c#L1328
[2]
https://elixir.bootlin.com/linux/latest/source/drivers/cpufreq/cpufreq.c#L1350
[3]
https://elixir.bootlin.com/linux/latest/source/drivers/cpufreq/cpufreq.c#L1374
next prev parent reply other threads:[~2020-04-06 13:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 11:45 [PATCH v5 0/5] Add support for devices in the Energy Model Lukasz Luba
2020-03-18 11:45 ` [PATCH v5 1/5] PM / EM: add devices to " Lukasz Luba
2020-04-03 16:05 ` Daniel Lezcano
2020-04-06 13:29 ` Lukasz Luba [this message]
2020-04-06 14:58 ` Daniel Lezcano
2020-04-06 16:07 ` Lukasz Luba
2020-04-06 21:17 ` Daniel Lezcano
2020-04-07 9:32 ` Lukasz Luba
2020-03-18 11:45 ` [PATCH v5 2/5] OPP: refactor dev_pm_opp_of_register_em() and update related drivers Lukasz Luba
2020-04-01 7:19 ` Lukasz Luba
2020-04-03 16:21 ` Daniel Lezcano
2020-04-06 14:05 ` Lukasz Luba
2020-03-18 11:45 ` [PATCH v5 3/5] thermal: devfreq_cooling: Use PM QoS to set frequency limits Lukasz Luba
2020-04-03 16:43 ` Daniel Lezcano
2020-04-03 17:18 ` Matthias Kaehlcke
2020-04-03 17:19 ` Daniel Lezcano
2020-03-18 11:45 ` [PATCH v5 4/5] thermal: devfreq_cooling: Refactor code and switch to use Energy Model Lukasz Luba
2020-04-01 10:49 ` Lukasz Luba
2020-04-03 17:44 ` Daniel Lezcano
2020-04-06 13:35 ` Lukasz Luba
2020-03-18 11:45 ` [PATCH v5 5/5] drm/panfrost: Register devfreq cooling and attempt to add " Lukasz Luba
2020-03-18 13:11 ` Alyssa Rosenzweig
2020-03-23 13:50 ` Lukasz Luba
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