From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Linux Samsung SoC <linux-samsung-soc@vger.kernel.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Dave Gerlach <d-gerlach@ti.com>, Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [PATCH 0/2] cpufreq/opp: rework regulator initialization
Date: Fri, 8 Feb 2019 13:03:10 +0100 [thread overview]
Message-ID: <CAJZ5v0gbh2LDq+6P_CQ+GWOxEdQrRUqQnx7v59hvs2_wwx9=kw@mail.gmail.com> (raw)
In-Reply-To: <20190208113904.GB7913@e107155-lin>
On Fri, Feb 8, 2019 at 12:39 PM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Fri, Feb 08, 2019 at 11:42:20AM +0100, Rafael J. Wysocki wrote:
> > On Fri, Feb 8, 2019 at 11:31 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > >
> > > On 08-02-19, 11:22, Rafael J. Wysocki wrote:
> > > > There are cpufreq driver suspend and resume callbacks, maybe use them?
> > > >
> > > > The driver could do the I2C transactions in its suspend/resume
> > > > callbacks and do nothing in online/offline if those are part of
> > > > system-wide suspend/resume.
> > >
> > > These are per-policy things that we need to do, not sure if driver
> > > suspend/resume is a good place for that. It is more for a case where
> > > CPU 0-3 are in one policy and 4-7 in another. Now 1-7 are
> > > hot-unplugged during system suspend and hotplugged later on. This is
> > > more like complete removal/addition of devices instead of
> > > suspend/resume.
> >
> > No, it isn't. We don't remove devices on offline. We migrate stuff
> > away from them and (opportunistically) power them down.
> >
> > If this is system suspend, the driver kind of knows that offline will
> > take place, so it can prepare for it. Likewise, when online takes
> > place during system-wide resume, it generally is known that this is
> > system-wide resume (there is a flag to indicate that in CPU hotplug),
> > it can be "smart" and avoid accessing suspended devices. Deferring
> > the frequency set up until the driver resume time should do the trick
> > I suppose.
>
> I agree. The reason we don't see this generally on boot is because all
> the CPUs are brought online before CPUfreq is initialised. While during
> system suspend, we call cpufreq_online which in turn calls ->init in
> the hotplug state machine.
>
> So as Rafael suggests we need to do some trick, but can it be done in
> the core itself ? I may be missing something, but how about the patch
> below:
>
> Regards,
> Sudeep
>
> --
> diff --git i/drivers/cpufreq/cpufreq.c w/drivers/cpufreq/cpufreq.c
> index e35a886e00bc..7d8b0b99f91d 100644
> --- i/drivers/cpufreq/cpufreq.c
> +++ w/drivers/cpufreq/cpufreq.c
> @@ -1241,7 +1241,8 @@ static int cpufreq_online(unsigned int cpu)
> policy->max = policy->user_policy.max;
> }
>
> - if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
> + if (cpufreq_driver->get && !cpufreq_driver->setpolicy &&
> + !cpufreq_suspended) {
> policy->cur = cpufreq_driver->get(policy->cpu);
> if (!policy->cur) {
> pr_err("%s: ->get() failed\n", __func__);
It looks like we need to skip the "initial freq check" block below.
Also this doesn't really help the case when the driver ->init() messes
up with things.
> @@ -1702,6 +1703,11 @@ void cpufreq_resume(void)
> pr_err("%s: Failed to start governor for policy: %p\n",
> __func__, policy);
> }
> + policy->cur = cpufreq_driver->get(policy->cpu);
> + if (!policy->cur) {
> + pr_err("%s: ->get() failed\n", __func__);
> + goto out_destroy_policy;
> + }
> }
> }
>
next prev parent reply other threads:[~2019-02-08 12:03 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20190207122255eucas1p1cdebed838c799eca46cce6a654a26187@eucas1p1.samsung.com>
2019-02-07 12:22 ` [PATCH 0/2] cpufreq/opp: rework regulator initialization Marek Szyprowski
[not found] ` <CGME20190207122255eucas1p1444023f01217a43cfb958fe0bd48ef4d@eucas1p1.samsung.com>
2019-02-07 12:22 ` [PATCH 1/2] cpufreq: dt/ti/opp: move regulators initialization to the drivers Marek Szyprowski
[not found] ` <CGME20190207122256eucas1p17e8742176bda911263d2d14d2797a886@eucas1p1.samsung.com>
2019-02-07 12:22 ` [PATCH 2/2] cpufreq: dt: rework resources initialization Marek Szyprowski
2019-02-08 1:26 ` kbuild test robot
2019-02-08 6:49 ` [PATCH 0/2] cpufreq/opp: rework regulator initialization Viresh Kumar
2019-02-08 8:12 ` Marek Szyprowski
2019-02-08 8:55 ` Viresh Kumar
2019-02-08 9:15 ` Marek Szyprowski
2019-02-08 9:23 ` Viresh Kumar
2019-02-08 10:02 ` Marek Szyprowski
2019-02-08 10:08 ` Rafael J. Wysocki
2019-02-08 10:18 ` Rafael J. Wysocki
2019-02-08 10:28 ` Viresh Kumar
2019-02-08 10:22 ` Rafael J. Wysocki
2019-02-08 10:31 ` Marek Szyprowski
2019-02-08 10:31 ` Viresh Kumar
2019-02-08 10:42 ` Rafael J. Wysocki
2019-02-08 10:52 ` Rafael J. Wysocki
2019-02-08 11:39 ` Sudeep Holla
2019-02-08 12:03 ` Rafael J. Wysocki [this message]
2019-02-08 12:09 ` Sudeep Holla
2019-02-08 12:23 ` Rafael J. Wysocki
2019-02-08 14:28 ` Sudeep Holla
2019-02-08 11:00 ` Sudeep Holla
2019-02-08 11:47 ` Marek Szyprowski
2019-02-08 11:51 ` Sudeep Holla
2019-02-08 12:04 ` Marek Szyprowski
2019-02-08 12:11 ` Rafael J. Wysocki
2019-02-08 12:16 ` Sudeep Holla
2019-02-08 17:41 ` Sudeep Holla
2019-02-11 8:47 ` Viresh Kumar
2019-02-11 14:08 ` Sudeep Holla
2019-02-11 8:44 ` Viresh Kumar
2019-02-11 9:52 ` Marek Szyprowski
2019-02-11 9:55 ` Viresh Kumar
2019-02-11 12:22 ` Marek Szyprowski
2019-02-12 5:08 ` Viresh Kumar
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