linux-kernel - Re: [PATCH 2/3] arm64: dts: qcom: sa8295p: Enable tertiary controller and its 4 USB ports

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Date: Thu, 8 Feb 2024 08:10:10 +0530
From: Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>
CC: Rob Herring <robh+dt@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <quic_ppratap@...cinc.com>, <quic_jackp@...cinc.com>
Subject: Re: [PATCH 2/3] arm64: dts: qcom: sa8295p: Enable tertiary controller
 and its 4 USB ports



On 2/6/2024 6:54 PM, Dmitry Baryshkov wrote:
> On Tue, 6 Feb 2024 at 14:28, Krishna Kurapati PSSNV
> <quic_kriskura@...cinc.com> wrote:
>>
>>
>>
>> On 2/6/2024 5:43 PM, Dmitry Baryshkov wrote:
>>> On Tue, 6 Feb 2024 at 14:03, Krishna Kurapati <quic_kriskura@...cinc.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

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 ?

Regards,
Krishna,