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 10:13:30 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Konrad Dybcio <konrad.dybcio@...aro.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...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 08/02/2024 10:07, Krishna Kurapati PSSNV wrote:
>>>>
>>>>> 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.
>>
> 
> Hi Dmitry,
> 
> I dug up the schematic and I see that the gpio's we are using in this 
> patch are actually "Enable Pins" to an external chip that provides vbus 
> to the peripherals connected. So from the perspective of SoC, it is a 
> GPIO and not to be represented as a regulator I believe.

According to such logic nothing is a regulator... sorry, you just
described regulator.

Best regards,
Krzysztof