From: Ulf Hansson <ulf.hansson@linaro.org>
To: Peng Fan <peng.fan@nxp.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Stephen Boyd <sboyd@kernel.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Lina Iyer <ilina@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Kevin Hilman <khilman@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Sudeep Holla <sudeep.holla@arm.com>,
Lukasz Luba <lukasz.luba@arm.com>
Subject: Re: [PATCH v2 3/3] PM / Domains: Add support for PM domain on/off notifiers for genpd
Date: Fri, 25 Sep 2020 13:48:12 +0200 [thread overview]
Message-ID: <CAPDyKFrrLq6mPCsSoRBBmgMxSvC4xeiSedi1c5CsEWF=+f73mw@mail.gmail.com> (raw)
In-Reply-To: <DB6PR0402MB2760BD51916BEA5DB80A268188360@DB6PR0402MB2760.eurprd04.prod.outlook.com>
On Fri, 25 Sep 2020 at 08:08, Peng Fan <peng.fan@nxp.com> wrote:
>
> Hi Ulf,
>
> > Subject: [PATCH v2 3/3] PM / Domains: Add support for PM domain on/off
> > notifiers for genpd
> >
> > A device may have specific HW constraints that must be obeyed to, before its
> > corresponding PM domain (genpd) can be powered off - and vice verse at
> > power on. These constraints can't be managed through the regular runtime
> > PM based deployment for a device, because the access pattern for it, isn't
> > always request based. In other words, using the runtime PM callbacks to deal
> > with the constraints doesn't work for these cases.
>
> Could the notification be added before/after power on, and before/after power
> off? not just after power on and before power off?
>
> Our SoC has a requirement that before power on/off the specific module,
> the corresponding clk needs to be on to make sure the hardware async
> bridge could finish handshake.
Thanks for your comments!
May I ask, to be sure - does the clock correspond to the genpd
provider or is it a clock for the genpd consumer device?
If the former, couldn't the clock be managed from the ->power_on|off()
callbacks for the genpd provider?
>
> So we need clk_prepare_on/off to guard power on and power off as below:
>
> clk_prepare_on
> power on
> clk_prepare_off
>
> clk_prepare_on
> power off
> clk_prepare_off
>
> Thanks,
> Peng.
>
[...]
Kind regards
Uffe
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next prev parent reply other threads:[~2020-09-25 11:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 11:04 [PATCH v2 0/3] PM / Domains: Add power on/off notifiers for genpd Ulf Hansson
2020-09-24 11:04 ` [PATCH v2 1/3] PM / Domains: Rename power state enums " Ulf Hansson
2020-09-24 11:04 ` [PATCH v2 2/3] PM / Domains: Allow to abort power off when no ->power_off() callback Ulf Hansson
2020-09-24 11:04 ` [PATCH v2 3/3] PM / Domains: Add support for PM domain on/off notifiers for genpd Ulf Hansson
2020-09-25 6:08 ` Peng Fan
2020-09-25 11:48 ` Ulf Hansson [this message]
2020-09-25 14:30 ` Peng Fan
2020-09-28 9:03 ` Ulf Hansson
2020-09-28 11:56 ` [PATCH v2 0/3] PM / Domains: Add power " Ulf Hansson
2020-10-02 17:17 ` Rafael J. Wysocki
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