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

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Date: Thu, 21 Dec 2023 21:34:16 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Mark Hasemeyer <markhas@...omium.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

On 21/12/2023 20:24, Mark Hasemeyer wrote:
>>>> 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.

This sentence would be enough.

> 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?
> 
Seems fine, thanks.

Best regards,
Krzysztof