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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Thu, 8 Feb 2024 07:07:46 +0200
Message-ID: <CAA8EJpoe-gaSgD_HruYSUAPgfBNCw9-G9wnEnvpkiCtmrqFQ7A@mail.gmail.com>
Subject: Re: [PATCH 2/3] arm64: dts: qcom: sa8295p: Enable tertiary controller
 and its 4 USB ports
To: Krishna Kurapati PSSNV <quic_kriskura@quicinc.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, 
	Konrad Dybcio <konrad.dybcio@linaro.org>, Rob Herring <robh+dt@kernel.org>, 
	Bjorn Andersson <andersson@kernel.org>, Conor Dooley <conor+dt@kernel.org>, linux-kernel@vger.kernel.org, 
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, 
	quic_ppratap@quicinc.com, quic_jackp@quicinc.com
Content-Type: text/plain; charset="UTF-8"

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