linux-kernel - Re: [PATCH v2 3/3] PCI: qcom: properly implement RC shutdown/power up

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Message-ID: <Zc25rIZbzWyw7hzq@hovoldconsulting.com>
Date: Thu, 15 Feb 2024 08:13:48 +0100
From: Johan Hovold <johan@...nel.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Bjorn Helgaas <helgaas@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Johan Hovold <johan+linaro@...nel.org>,
	Bjorn Andersson <quic_bjorande@...cinc.com>
Subject: Re: [PATCH v2 3/3] PCI: qcom: properly implement RC shutdown/power up

On Wed, Feb 14, 2024 at 10:33:19PM +0100, Konrad Dybcio wrote:
> On 12.02.2024 22:32, Bjorn Helgaas wrote:
> > "Properly" is a noise word that suggests "we're doing it right this
> > time" but doesn't hint at what actually makes this better.
> > 
> > On Sat, Feb 10, 2024 at 06:10:07PM +0100, Konrad Dybcio wrote:
> >> Currently, we've only been minimizing the power draw while keeping the
> >> RC up at all times. This is suboptimal, as it draws a whole lot of power
> >> and prevents the SoC from power collapsing.
> > 
> > Is "power collapse" a technical term specific to this device, or is
> > there some more common term that could be used?  I assume the fact
> > that the RC remains powered precludes some lower power state of the
> > entire SoC?
> 
> That's spot on, "power collapse" commonly refers to shutting down as many
> parts of the SoC as possible, in order to achieve miliwatt-order power draw.

I'm pretty sure "power collapse" is a Qualcomm:ism so better to use
common terminology as Bjorn suggested, and maybe put the Qualcomm
wording in parenthesis or similar.

Johan