linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

      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]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201014042033.tmsbanj5xgh2lmul@vireshk-i7 \
    --to=viresh.kumar@linaro.org \
    --cc=chris.redpath@arm.com \
    --cc=daniel.lezcano@linaro.org \
    --cc=devicetree@vger.kernel.org \
    --cc=ionela.voinescu@arm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=lukasz.luba@arm.com \
    --cc=morten.rasmussen@arm.com \
    --cc=nicola.mazzucato@arm.com \
    --cc=rjw@rjwysocki.net \
    --cc=robh+dt@kernel.org \
    --cc=sudeep.holla@arm.com \
    --cc=vireshk@kernel.org \
    --subject='Re: [PATCH v2 2/2] [RFC] CPUFreq: Add support for cpu-perf-dependencies' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).