linux-kernel - Re: [PATCH 3/3] arm64: dts: qcom: x1e80100-qcp: Add WiFi/BT pwrseq

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Message-ID: <CAMRc=MeYDi0_+y7a-KQhh=ft4rstng5H24LJBgsJg1BdXfc-nQ@mail.gmail.com>
Date: Thu, 17 Oct 2024 14:21:08 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Mark Brown <broonie@...nel.org>
Cc: Stephan Gerhold <stephan.gerhold@...aro.org>, Johan Hovold <johan@...nel.org>, 
	Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Abel Vesa <abel.vesa@...aro.org>, 
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: Re: [PATCH 3/3] arm64: dts: qcom: x1e80100-qcp: Add WiFi/BT pwrseq

On Thu, Oct 17, 2024 at 2:01 PM Mark Brown <broonie@...nel.org> wrote:
>
> On Thu, Oct 17, 2024 at 01:28:00PM +0200, Bartosz Golaszewski wrote:
> > On Thu, Oct 17, 2024 at 12:59 PM Mark Brown <broonie@...nel.org> wrote:
>
> > > Fix your driver to request the supplies that actually exist on the
> > > device rather than just some random supplies you hope will work?
>
> > Let me rephrase: the device has this supply but on this particular
> > board nothing is connected to it. It does sound to me like an example
> > of an "optional" supply. Do you have anything against making it
> > possible to define optional supplies when using the bulk regulator
> > APIs?
>
> Oh, right - please if asking questions ask a complete question rather

Sure, sorry.

> than having a long email thread and adding an "any thoughts" at the end
> which makes it unclear what the actual question is.  In general the
> expectation for optional supplies is that you will need to do something
> different depending on if the supply is there, that will tend to mean
> that it's fairly natural to do a separate request for it as well.
> What's the concrete use case here?

A device is wired differently on different platforms. It requests a
bunch of supplies using devm_regulator_bulk_get(). One of them is
unconnected on one of the platforms resulting in the "using dummy
regulator" warning.

Concrete use-case is: make all but one regulator mandatory when
calling regulator_bulk_get(). My proposal is extending struct
regulator_bulk_data with a boolean flag called "optional" which would
result in the underlying _regulator_get() receiving the OPTIONAL_GET
flag only for the regulators that are marked as such.

Bartosz