linux-kernel - Re: [PATCH v2 06/22] ARM: dts: samsung: exynos5420: Enable cros-ec-spi as wake source

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Message-ID: <CANg-bXAY5AGTu_jwtO8syCi8XVh5ti1V6ZFMzyCSBjzCUKUn1Q@mail.gmail.com>
Date: Thu, 21 Dec 2023 12:24:51 -0700
From: Mark Hasemeyer <markhas@...omium.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: LKML <linux-kernel@...r.kernel.org>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Tzung-Bi Shih <tzungbi@...nel.org>, Raul Rangel <rrangel@...omium.org>, 
	Konrad Dybcio <konrad.dybcio@...aro.org>, Andy Shevchenko <andriy.shevchenko@...el.com>, 
	Rob Herring <robh@...nel.org>, Sudeep Holla <sudeep.holla@....com>, 
	Alim Akhtar <alim.akhtar@...sung.com>, Conor Dooley <conor+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Rob Herring <robh+dt@...nel.org>, 
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v2 06/22] ARM: dts: samsung: exynos5420: Enable
 cros-ec-spi as wake source

> >> You do not need this property, if driver assumes that. Just enable it
> >> unconditionally.
> >
> > The goal of this patch series is to change exactly that: to prevent
> > the driver from unconditionally enabling the irq for wake.
>
> But why? What is the problem being solved? Is unconditional wakeup in
> the driver incorrect? If so, mention it shortly in the commit msg, what
> is rationale because existing one does not justify this change.

The cover letter talks about it:
"Currently the cros_ec driver assumes that its associated interrupt is
wake capable. This is an incorrect assumption as some Chromebooks use
a separate wake pin, while others overload the interrupt for wake and
IO."
With the current assumption, spurious wakes can occur on systems that
use a separate wake pin.
I can add wording to the dts patches to help clarify.

> > The driver works across numerous buses (spi, uart, i2c, lpc) and
> > supports DT and ACPI.
> > SPI+DT systems all happen to need irq wake enabled.
> >
> >> I don't think anything from previous discussion was
> >> resolved.
> >
> > Which previous discussion do you mean? In v1 it was suggested to split
>
> https://lore.kernel.org/all/20231213221124.GB2115075-robh@kernel.org/

Hmm, I thought that was addressed [2]. I was referencing the existing
binding documentation. From there, there was discussion about updating
the docs to clarify what was actually intended (patch 3 in this
series). I also addressed the ABI break concern in the thread and
mentioned it in patch 22.
"For device tree base systems, it is not an issue as the relevant
device tree entries have been updated and DTS is built from source for
each ChromeOS update."

Is there a specific concern you feel is not resolved? Or can I make
something more clear?

[2] https://lore.kernel.org/all/CANg-bXCG61HFW7JFuAd3k+OrCG_F9F3e8brjM-pmBauS53aobQ@mail.gmail.com/