linux-kernel - Re: [PATCH RFT v2 0/3] Fix up SC8280XP idle states

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Date: Thu, 15 Feb 2024 08:38:19 +0100
From: Johan Hovold <johan@...nel.org>
To: Bjorn Andersson <andersson@...nel.org>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>,
	Andy Gross <agross@...nel.org>, Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Johan Hovold <johan+linaro@...nel.org>,
	Marijn Suijten <marijn.suijten@...ainline.org>,
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Konrad Dybcio <konrad.dybcio@...ainline.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH RFT v2 0/3] Fix up SC8280XP idle states

On Tue, Feb 13, 2024 at 11:35:06PM -0600, Bjorn Andersson wrote:
> On Wed, Dec 20, 2023 at 11:12:53PM +0100, Konrad Dybcio wrote:
> > Comparing the data available in the downstream sources with what's there
> > upstream, it was easy to spot some differences. This series aligns what
> > we have upstream with what is there on the vendor kernel.
> > 
> > The big asterisk there is that the downstream sources for SC8280XP can't
> > always be trusted. A simple test shows that the lower idle states that
> > were previously missing are implemented in the firmware (Linux reports no
> > errors and enters them).
> > 
> > HOWEVER
> > 
> > The only cluster idle state that's been present until now (the deepest
> > one) is now barely used if at all, as the scheduler seems to deem it
> > inefficient or so.
> > 
> > Hence, a request for testing and comments, especially from those who
> > use the X13s daily or have reliable setup to measure the power usage.
> > 
> > Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> 
> What did we conclude on this one? Does the extra state make sense?
> The last patch looks useful...

I asked Konrad a while back to provide some performance numbers to
accompany this change.

I think he said that this series made no difference in either direction,
but IIUC that only after a really quick attempt at evaluating the
impact during a meeting we had.

Johan