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Date: Tue, 20 Feb 2024 22:21:04 +0100
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Subject: Re: [PATCH v5 14/18] PCI/pwrctl: add a power control driver for
 WCN7850
To: Mark Brown <broonie@kernel.org>, Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Marcel Holtmann <marcel@holtmann.org>,
 Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
 "David S . Miller" <davem@davemloft.net>, Eric Dumazet
 <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
 Paolo Abeni <pabeni@redhat.com>, Rob Herring <robh@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Kalle Valo <kvalo@kernel.org>,
 Bjorn Andersson <andersson@kernel.org>, Liam Girdwood <lgirdwood@gmail.com>,
 Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>,
 Bjorn Helgaas <bhelgaas@google.com>, Saravana Kannan <saravanak@google.com>,
 Geert Uytterhoeven <geert+renesas@glider.be>, Arnd Bergmann <arnd@arndb.de>,
 Neil Armstrong <neil.armstrong@linaro.org>,
 Marek Szyprowski <m.szyprowski@samsung.com>, Alex Elder <elder@linaro.org>,
 Srini Kandagatla <srinivas.kandagatla@linaro.org>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 Abel Vesa <abel.vesa@linaro.org>, Manivannan Sadhasivam <mani@kernel.org>,
 Lukas Wunner <lukas@wunner.de>,
 Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
 linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-wireless@vger.kernel.org, linux-arm-msm@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
 linux-pm@vger.kernel.org,
 Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
References: <20240216203215.40870-1-brgl@bgdev.pl>
 <20240216203215.40870-15-brgl@bgdev.pl>
 <d5d603dc-ec66-4e21-aa41-3b25557f1fb7@sirena.org.uk>
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From: Konrad Dybcio <konrad.dybcio@linaro.org>
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In-Reply-To: <ea08a286-ff53-4d58-ae41-38cca151508c@sirena.org.uk>
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On 20.02.2024 13:47, Mark Brown wrote:
> 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@kernel.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.

*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.

Konrad