netdev - Re: [PATCH v5 14/18] PCI/pwrctl: add a power control driver for WCN7850

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Message-ID: <CAMRc=MedCX_TGGawMhr39oXtJPF4pOQF=Jh2z4uXkOxwhfJWRw@mail.gmail.com>
Date: Thu, 22 Feb 2024 10:22:50 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Mark Brown <broonie@...nel.org>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>, Marcel Holtmann <marcel@...tmann.org>, 
	Luiz Augusto von Dentz <luiz.dentz@...il.com>, "David S . Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Conor Dooley <conor+dt@...nel.org>, Kalle Valo <kvalo@...nel.org>, 
	Bjorn Andersson <andersson@...nel.org>, Liam Girdwood <lgirdwood@...il.com>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Saravana Kannan <saravanak@...gle.com>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Arnd Bergmann <arnd@...db.de>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Marek Szyprowski <m.szyprowski@...sung.com>, 
	Alex Elder <elder@...aro.org>, Srini Kandagatla <srinivas.kandagatla@...aro.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Abel Vesa <abel.vesa@...aro.org>, 
	Manivannan Sadhasivam <mani@...nel.org>, Lukas Wunner <lukas@...ner.de>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, linux-bluetooth@...r.kernel.org, 
	netdev@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-pci@...r.kernel.org, linux-pm@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v5 14/18] PCI/pwrctl: add a power control driver for WCN7850

On Wed, Feb 21, 2024 at 12:44 AM Mark Brown <broonie@...nel.org> wrote:
>
> On Tue, Feb 20, 2024 at 10:21:04PM +0100, Konrad Dybcio wrote:
> > On 20.02.2024 13:47, Mark Brown wrote:
>
> > > Are you *sure* this actually happens (and that the regulators don't
> > > figure it out by themselves), especially given that the consumers are
> > > just specifying the load once rather than varying it dynamically at
> > > runtime which is supposed to be the use case for this API?  This API is
> > > intended to be used dynamically, if the regulator always needs to be in
> > > a particular mode just configure that statically.
>
> > *AFAIU*
>
> > The regulators aggregate the requested current (there may be
> > multiple consumers) and then it's decided if it's high enough
> > to jump into HPM.
>
> Yes, that's the theory - I just question if it actually does something
> useful in practice.  Between regulators getting more and more able to
> figure out mode switching autonomously based on load monitoring and them
> getting more efficient it's become very unclear if this actually
> accomplishes anything, the only usage is the Qualcomm stuff and that's
> all really unsophisticated and has an air of something that's being
> cut'n'pasted forwards rather than delivering practical results.  There
> is some value at ultra low loads, but that's more for suspend modes than
> for actual use.

Removing it would be out of scope for this series and I don't really
want to introduce any undefined behavior when doing a big development
like that. I'll think about it separately.

Bart