linux-kernel - Re: [RFC 15/18] mfd: max77693: Do not enforce (incorrect) interrupt trigger type

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Date:   Mon, 21 Dec 2020 11:46:12 -0700
From:   Rob Herring <robh@...nel.org>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        linux-arm-msm@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Angus Ainslie <angus@...ea.ca>,
        Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
        Hans de Goede <hdegoede@...hat.com>,
        linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        linux-rtc@...r.kernel.org,
        Iskren Chernev <iskren.chernev@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sebastian Reichel <sre@...nel.org>,
        Matheus Castello <matheus@...tello.eng.br>,
        linux-clk@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        Michael Turquette <mturquette@...libre.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-pm@...r.kernel.org,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>,
        linux-arm-kernel@...ts.infradead.org,
        Alessandro Zummo <a.zummo@...ertech.it>
Subject: Re: [RFC 15/18] mfd: max77693: Do not enforce (incorrect) interrupt
 trigger type

On Thu, 10 Dec 2020 22:25:31 +0100, Krzysztof Kozlowski wrote:
> Interrupt line can be configured on different hardware in different way,
> even inverted.  Therefore driver should not enforce specific trigger
> type - edge falling - but instead rely on Devicetree to configure it.
> 
> The Maxim 77693 datasheet describes the interrupt line as active low
> with a requirement of acknowledge from the CPU therefore the edge
> falling is not correct.
> 
> The interrupt line is shared between PMIC and RTC driver, so using level
> sensitive interrupt is here especially important to avoid races.  With
> an edge configuration in case if first PMIC signals interrupt followed
> shortly after by the RTC, the interrupt might not be yet cleared/acked
> thus the second one would not be noticed.
> 
> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> 
> ---
> 
> This patch should wait till DTS changes are merged, as it relies on
> proper Devicetree.
> ---
>  Documentation/devicetree/bindings/mfd/max77693.txt |  2 +-
>  drivers/mfd/max77693.c                             | 12 ++++--------
>  2 files changed, 5 insertions(+), 9 deletions(-)
> 

Acked-by: Rob Herring <robh@...nel.org>