linux-kernel - Re: [PATCH v3 6/7] dt-bindings: soc: qcom: Extend RPMh power controller binding to describe thermal warming device

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Date:   Thu, 17 Oct 2019 17:43:08 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     Eduardo Valentin <edubezval@...il.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>, amit.kucheria@...durent.com,
        Mark Rutland <mark.rutland@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 6/7] dt-bindings: soc: qcom: Extend RPMh power
 controller binding to describe thermal warming device

On Thu, 17 Oct 2019 at 17:28, Thara Gopinath <thara.gopinath@...aro.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@...aro.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@...aro.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.

>From Linux point of view, it means you can use dev_pm_domain_attach()
to hook up the corresponding device with the PM domain.

Using "power-domain-names" is just to allow to specify a name rather
than an index, which makes sense if there is more than one index.
Perhaps you can state that the "power-domain-names" should be there
anyway, to be a little bit future proof if ever multiple index
(multiple PM domains).

Kind regards
Uffe