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 12:47:48 +0000
From: Mark Brown <broonie@...nel.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: 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>,
	Konrad Dybcio <konrad.dybcio@...aro.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 12:22:42PM +0100, Bartosz Golaszewski wrote:
> On Mon, Feb 19, 2024 at 6:50 PM Mark Brown <broonie@...nel.org> wrote:
> > On Fri, Feb 16, 2024 at 09:32:11PM +0100, Bartosz Golaszewski wrote:

> > > +static struct pci_pwrctl_wcn7850_vreg pci_pwrctl_wcn7850_vregs[] = {
> > > +     {
> > > +             .name = "vdd",
> > > +             .load_uA = 16000,
> > > +     },

> > I know a bunch of the QC stuff includes these load numbers but are they
> > actually doing anything constructive?  It keeps coming up that they're
> > causing a bunch of work and it's not clear that they have any great
> > effect on modern systems.

> Yes, we have what is called a high-power mode and a low-power mode in
> regulators and these values are used to determine which one to use.

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.

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