linux-kernel - Re: [PATCH v2 2/4] arm64: dts: qcom: sm6350: Add camera clock controller

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Message-Id: <CQ2ZY0W1M4F5.32SLTSYMILGOS@otso>
Date:   Fri, 27 Jan 2023 14:11:30 +0100
From:   "Luca Weiss" <luca.weiss@...rphone.com>
To:     "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        "Andy Gross" <agross@...nel.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        "Konrad Dybcio" <konrad.dybcio@...aro.org>,
        "Loic Poulain" <loic.poulain@...aro.org>,
        "Robert Foss" <rfoss@...nel.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>
Cc:     <~postmarketos/upstreaming@...ts.sr.ht>,
        <phone-devel@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] arm64: dts: qcom: sm6350: Add camera clock
 controller

On Fri Jan 27, 2023 at 1:49 PM CET, Bryan O'Donoghue wrote:
> On 27/01/2023 12:45, Luca Weiss wrote:
> > Can I reference <&camcc TITAN_TOP_GDSC> from itself? I know that having
> > it on is required to turn on at least some clocks (maybe all clocks).
> > But from what I understand how power domains are normally handled, the
> > driver core enables them before the driver is probed, so self
> > referencing wouldn't work.
> > 
> > And at least no other SoC upstream references TITAN_TOP_GDSC in camcc.
> > 
> > Regards
> > Luca
>
> Doh I meant to say a power-domain to an mmcx a la
>
> power-domains = <&rpmhpd SM8250_MMCX>;
> required-opps = <&rpmhpd_opp_low_svs>;
>
> TITAN_TOP should be in your cci and camss dt nodes.

Okay, that makes more sense.

What I don't quite understand is why sm8250 only has MMCX listed there
since downstream has both vdd_mx-supply = <&VDD_MX_LEVEL> and
vdd_mm-supply = <&VDD_MMCX_LEVEL> and both "supplies" are used for
different clocks using .vdd_class

But back to sm6350, downstream has vdd_mx-supply = <&VDD_MX_LEVEL> and
vdd_cx-supply = <&VDD_CX_LEVEL> and like sm8250 uses cx and mx for
different clocks.
Not sure if I should add both, and I guess mainline also currently
doesn't use higher ops for the power domain when higher clock rate is
needed, from what I understand?

>
> ---
> bod