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    SubjectRe: [PATCH 2/3] arm64: dts: qcom: sa8295p: Enable tertiary controller and its 4 USB ports
    On Thu, 8 Feb 2024 at 06:48, Krishna Kurapati PSSNV
    <quic_kriskura@quicinc.com> wrote:
    >
    >
    >
    > On 2/8/2024 10:11 AM, Dmitry Baryshkov wrote:
    > > On Thu, 8 Feb 2024 at 04:40, Krishna Kurapati PSSNV
    > > <quic_kriskura@quicinc.com> wrote:
    > >> On 2/6/2024 6:54 PM, Dmitry Baryshkov wrote:
    > >>> On Tue, 6 Feb 2024 at 14:28, Krishna Kurapati PSSNV
    > >>> <quic_kriskura@quicinc.com> wrote:
    > >>>>
    > >>>>
    > >>>>
    > >>>> On 2/6/2024 5:43 PM, Dmitry Baryshkov wrote:
    > >>>>> On Tue, 6 Feb 2024 at 14:03, Krishna Kurapati <quic_kriskura@quicinc.com> wrote:
    > >>>>>>
    > >>>>>> Enable tertiary controller for SA8295P (based on SC8280XP).
    > >>>>>> Add pinctrl support for usb ports to provide VBUS to connected peripherals.
    > >>>>>
    > >>>>> These are not just pinctrl entries. They hide VBUS regulators. Please
    > >>>>> implement them properly as corresponding vbus regulators.
    > >>>>>
    > >>>>
    > >>>> Hi Dmitry. Apologies, can you elaborate on your comment. I thought this
    > >>>> implementation was fine as Konrad reviewed it in v13 [1]. I removed his
    > >>>> RB tag as I made one change of dropping "_state" in labels.
    > >>>
    > >>> My comment is pretty simple: if I'm not mistaken, your DT doesn't
    > >>> reflect your hardware design.
    > >>> You have actual VBUS regulators driven by these GPIO pins. Is this correct?
    > >>> If so, you should describe them properly in the device tree rather
    > >>> than describing them just as USB host's pinctrl state.
    > >>>
    > >>
    > >> Hi Dmitry,
    > >>
    > >> I have very little idea about the gpio controller regulators. I will
    > >> go through it and see how I can implement it. I just found this :
    > >> https://www.kernel.org/doc/Documentation/devicetree/bindings/regulator/gpio-regulator.txt
    > >
    > > Much simpler, it can be found at
    > > Documentation/devicetree/bindings/regulator/fixed-regulator.yaml
    >
    > Thanks for the reference.
    >
    > >
    > >> One query. If we model it as a regulator, do we need to add it as a
    > >> supply and call regulator_enable in dwc3_qcom probe again ?
    > >
    > > Not in probe(), but yes. It needs to be enabled when the VBUS has to
    > > be powered up, when the device is initialised or switched to the host
    > > mode, and disabled when the VBUS has to be powered down, if the device
    > > is being switched to the device mode.
    > >
    >
    > Actually since we never go to device mode, can't we just stick to this
    > pinctrl approach and skip turning on regulator in driver ?

    Scroll several emails back. DT should describe the hardware. Hardware
    has VBUS regulators.

    --
    With best wishes
    Dmitry

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