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

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Date: Tue, 20 Feb 2024 23:44:14 +0000
From: Mark Brown <broonie@...nel.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Bartosz Golaszewski <brgl@...ev.pl>,
	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 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.

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