From: Viresh Kumar <viresh.kumar@linaro.org>
To: Lukasz Luba <lukasz.luba@arm.com>
Cc: devicetree@vger.kernel.org, linux-pm@vger.kernel.org,
vireshk@kernel.org, daniel.lezcano@linaro.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, robh+dt@kernel.org,
Nicola Mazzucato <nicola.mazzucato@arm.com>,
sudeep.holla@arm.com, chris.redpath@arm.com,
Ionela Voinescu <ionela.voinescu@arm.com>,
morten.rasmussen@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 2/2] [RFC] CPUFreq: Add support for cpu-perf-dependencies
Date: Wed, 14 Oct 2020 09:50:33 +0530 [thread overview]
Message-ID: <20201014042033.tmsbanj5xgh2lmul@vireshk-i7> (raw)
In-Reply-To: <6a739b1b-e345-fa09-d815-6e9601aff5f6@arm.com>
On 13-10-20, 14:53, Lukasz Luba wrote:
> I've started wondering based on the OPP code if this is a good solution.
> We would end up with one (?) instance of opp_table and list of devices
> pinned to it, in: opp_table->dev_list
> It can be seen e.g. in function dev_pm_opp_get_sharing_cpus(),
> where we retrieve the cpumask simply looping through the devices:
>
> list_for_each_entry(opp_dev, &opp_table->dev_list, node)
> cpumask_set_cpu(opp_dev->dev->id, cpumask);
>
>
> This means we have a single OPP table for all pinned CPUs.
> I wonder if this is not too strong assumption for still being compliant
> with SCMI spec, when in theory performance levels might differ...
> (please correct me here it that would never happen)
>
> There is also 2nd function dev_pm_opp_of_get_sharing_cpus() which looks
> more promising. But I still don't know if the framework will allow us
> to have private OPP tables when we use 'shared' in DT.
>
> Could you clarify if we would get 'private' opp table for each CPU,
> which could be then populated independently, but still 2nd function will
> work?
I think there is some misunderstanding here in your part. The
opp-table in the code is shared between CPUs only when the
"opp-shared" property is present in the OPP table. If that property
isn't available, even if same DT opp-table is pointed at by all the
CPUs, the code will have separate copies of the OPP table.
Though in your case (with performance-levels) it shouldn't matter as
code will never create an OPP table I suppose.
--
viresh
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prev parent reply other threads:[~2020-10-14 4:22 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 9:53 [PATCH v2 0/2] CPUFreq: Add support for cpu performance dependencies Nicola Mazzucato
2020-09-24 9:53 ` [PATCH v2 1/2] dt-bindings: arm: Add devicetree binding for cpu-performance-dependencies Nicola Mazzucato
2020-10-08 13:42 ` Ionela Voinescu
2020-09-24 9:53 ` [PATCH v2 2/2] [RFC] CPUFreq: Add support for cpu-perf-dependencies Nicola Mazzucato
2020-10-06 7:19 ` Viresh Kumar
2020-10-07 12:58 ` Nicola Mazzucato
2020-10-08 11:02 ` Viresh Kumar
2020-10-08 15:03 ` Ionela Voinescu
2020-10-08 15:57 ` Rafael J. Wysocki
2020-10-08 17:08 ` Ionela Voinescu
2020-10-12 16:06 ` Sudeep Holla
2020-10-08 16:00 ` Nicola Mazzucato
2020-10-09 5:39 ` Viresh Kumar
2020-10-09 11:10 ` Nicola Mazzucato
2020-10-09 11:17 ` Viresh Kumar
2020-10-09 14:01 ` Rob Herring
2020-10-09 15:28 ` Nicola Mazzucato
2020-10-12 4:19 ` Viresh Kumar
2020-10-12 10:22 ` Lukasz Luba
2020-10-12 10:50 ` Rafael J. Wysocki
2020-10-12 11:05 ` Lukasz Luba
2020-10-12 10:59 ` Ionela Voinescu
2020-10-12 13:48 ` Lukasz Luba
2020-10-12 16:30 ` Ionela Voinescu
2020-10-12 18:19 ` Lukasz Luba
2020-10-12 22:01 ` Ionela Voinescu
2020-10-13 11:53 ` Rafael J. Wysocki
2020-10-13 12:39 ` Ionela Voinescu
2020-10-15 15:56 ` Rafael J. Wysocki
2020-10-15 18:38 ` Ionela Voinescu
2020-10-12 13:59 ` Rob Herring
2020-10-12 16:02 ` Sudeep Holla
2020-10-12 15:54 ` Sudeep Holla
2020-10-12 15:49 ` Sudeep Holla
2020-10-12 16:52 ` Ionela Voinescu
2020-10-12 17:18 ` Lukasz Luba
2020-10-14 4:25 ` Viresh Kumar
2020-10-14 9:11 ` Lukasz Luba
2020-10-19 8:50 ` Nicola Mazzucato
2020-10-19 9:46 ` Viresh Kumar
2020-10-19 13:36 ` Nicola Mazzucato
2020-10-20 10:48 ` Viresh Kumar
2020-10-13 13:53 ` Lukasz Luba
2020-10-14 4:20 ` Viresh Kumar [this message]
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