From: Ulf Hansson <ulf.hansson@linaro.org>
To: Rob Herring <robh@kernel.org>
Cc: Thara Gopinath <thara.gopinath@linaro.org>,
Eduardo Valentin <edubezval@gmail.com>,
Zhang Rui <rui.zhang@intel.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Andy Gross <agross@kernel.org>,
Amit Kucheria <amit.kucheria@verdurent.com>,
Mark Rutland <mark.rutland@arm.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux PM <linux-pm@vger.kernel.org>,
DTML <devicetree@vger.kernel.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 6/7] dt-bindings: soc: qcom: Extend RPMh power controller binding to describe thermal warming device
Date: Wed, 30 Oct 2019 10:27:21 +0100 [thread overview]
Message-ID: <CAPDyKFrZ9uFt8zqncYTQ-SB6s6LqSRHbwo+Eh_zu57kxj_2eMw@mail.gmail.com> (raw)
In-Reply-To: <CAL_Jsq+OoyC5FZxYrX_KN1QLDXRvKuFbH=9pLiELsOtoPixnPA@mail.gmail.com>
On Tue, 29 Oct 2019 at 21:16, Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Oct 29, 2019 at 5:07 AM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >
> > On Tue, 29 Oct 2019 at 02:36, Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Thu, Oct 17, 2019 at 12:10:15PM -0400, Thara Gopinath wrote:
> > > > On 10/17/2019 11:43 AM, Ulf Hansson wrote:
> > > > > On Thu, 17 Oct 2019 at 17:28, Thara Gopinath <thara.gopinath@linaro.org> wrote:
> > > > >>
> > > > >> Hello Ulf,
> > > > >> Thanks for the review!
> > > > >>
> > > > >> On 10/17/2019 05:04 AM, Ulf Hansson wrote:
> > > > >>> On Wed, 16 Oct 2019 at 21:37, Thara Gopinath <thara.gopinath@linaro.org> wrote:
> > > > >>>>
> > > > >>>> RPMh power controller hosts mx domain that can be used as thermal
> > > > >>>> warming device. Add a sub-node to specify this.
> > > > >>>>
> > > > >>>> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
> > > > >>>> ---
> > > > >>>> Documentation/devicetree/bindings/power/qcom,rpmpd.txt | 10 ++++++++++
> > > > >>>> 1 file changed, 10 insertions(+)
> > > > >>>>
> > > > >>>> diff --git a/Documentation/devicetree/bindings/power/qcom,rpmpd.txt b/Documentation/devicetree/bindings/power/qcom,rpmpd.txt
> > > > >>>> index eb35b22..fff695d 100644
> > > > >>>> --- a/Documentation/devicetree/bindings/power/qcom,rpmpd.txt
> > > > >>>> +++ b/Documentation/devicetree/bindings/power/qcom,rpmpd.txt
> > > > >>>> @@ -18,6 +18,16 @@ Required Properties:
> > > > >>>> Refer to <dt-bindings/power/qcom-rpmpd.h> for the level values for
> > > > >>>> various OPPs for different platforms as well as Power domain indexes
> > > > >>>>
> > > > >>>> += SUBNODES
> > > > >>>> +RPMh alsp hosts power domains that can behave as thermal warming device.
> > > > >>>> +These are expressed as subnodes of the RPMh. The name of the node is used
> > > > >>>> +to identify the power domain and must therefor be "mx".
> > > > >>>> +
> > > > >>>> +- #cooling-cells:
> > > > >>>> + Usage: optional
> > > > >>>> + Value type: <u32>
> > > > >>>> + Definition: must be 2
> > > > >>>> +
> > > > >>>
> > > > >>> Just wanted to express a minor thought about this. In general we use
> > > > >>> subnodes of PM domain providers to represent the topology of PM
> > > > >>> domains (subdomains), this is something different, which I guess is
> > > > >>> fine.
> > > > >>>
> > > > >>> I assume the #cooling-cells is here tells us this is not a PM domain
> > > > >>> provider, but a "cooling device provider"?
> > > > >> Yep.
> > > > >>>
> > > > >>> Also, I wonder if it would be fine to specify "power-domains" here,
> > > > >>> rather than using "name" as I think that is kind of awkward!?
> > > > >> Do you mean "power-domain-names" ? I am using this to match against the
> > > > >> genpd names defined in the provider driver.
> > > > >
> > > > > No. If you are using "power-domains" it means that you allow to
> > > > > describe the specifier for the provider.
> > > > Yep. But won't this look funny in DT ? The provider node will have a sub
> > > > node with a power domain referencing to itself Like below: Is this ok ?
> > > >
> > > > rpmhpd: power-controller {
> > > > compatible = "qcom,sdm845-rpmhpd";
> > > > #power-domain-cells = <1>;
> > > >
> > > > ...
> > > > ...
> > > > mx_cdev: mx {
> > > > #cooling-cells = <2>;
> > > > power-domains = <&rpmhpd SDM845_MX>;
> > > > };
> > > >
> > >
> > > The whole concept here seems all wrong to me. Isn't it what's in the
> > > power domain that's the cooling device. A CPU power domain is not a
> > > cooling device, the CPU is. Or we wouldn't make a clock a cooling
> > > device, but what the clock drives.
> >
> > Well, I don't think that's entirely correct description either.
> >
> > As I see it, it's really the actual PM domain (that manages voltages
> > for a power island), that needs to stay in full power state and
> > increase its voltage level, as to warm up some of the silicon. It's
> > not a regular device, but more a characteristics of how the PM domain
> > can be used.
>
> First I've heard of Si needing warming...
I guess people go to cooler places with their devices. :-)
>
> I think I'd just expect the power domain provider to know which
> domains to power on then.
Yeah, I agree. This seems reasonable.
Thanks!
Kind regards
Uffe
next prev parent reply other threads:[~2019-10-30 9:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 19:37 [PATCH v3 0/7]Introduce Power domain based warming device driver Thara Gopinath
2019-10-16 19:37 ` [PATCH v3 1/7] PM/Domains: Add support for retrieving genpd performance states information Thara Gopinath
2019-10-17 8:49 ` Ulf Hansson
2019-10-17 16:11 ` Thara Gopinath
2019-10-16 19:37 ` [PATCH v3 2/7] soc: qcom: rpmhpd: Introduce function to retrieve power domain performance state count Thara Gopinath
2019-10-16 19:37 ` [PATCH v3 3/7] thermal: core: Add late init hook to cooling device ops Thara Gopinath
2019-12-03 17:04 ` Amit Kucheria
2019-12-03 17:09 ` Thara Gopinath
2019-12-03 17:11 ` Amit Kucheria
2019-10-16 19:37 ` [PATCH v3 4/7] thermal: Add generic power domain warming device driver Thara Gopinath
2019-10-17 8:47 ` Ulf Hansson
2019-10-17 15:46 ` Thara Gopinath
2019-10-16 19:37 ` [PATCH v3 5/7] soc: qcom: Extend RPMh power controller driver to register warming devices Thara Gopinath
2019-10-16 19:37 ` [PATCH v3 6/7] dt-bindings: soc: qcom: Extend RPMh power controller binding to describe thermal warming device Thara Gopinath
2019-10-17 9:04 ` Ulf Hansson
2019-10-17 15:28 ` Thara Gopinath
2019-10-17 15:43 ` Ulf Hansson
2019-10-17 16:10 ` Thara Gopinath
2019-10-29 1:36 ` Rob Herring
2019-10-29 10:06 ` Ulf Hansson
2019-10-29 20:16 ` Rob Herring
2019-10-30 9:27 ` Ulf Hansson [this message]
2019-10-30 14:27 ` Thara Gopinath
2019-10-16 19:37 ` [PATCH v3 7/7] arm64: dts: qcom: Add mx power domain as " Thara Gopinath
2019-10-29 1:31 ` Rob Herring
2019-10-30 14:23 ` Thara Gopinath
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