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

From: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	linux-arm-msm@vger.kernel.org, Andy Gross <agross@kernel.org>,
	Angus Ainslie <angus@akkea.ca>, Stephen Boyd <sboyd@kernel.org>,
	devicetree@vger.kernel.org, Hans de Goede <hdegoede@redhat.com>,
	linux-kernel@vger.kernel.org, Mark Brown <broonie@kernel.org>,
	linux-rtc@vger.kernel.org,
	Iskren Chernev <iskren.chernev@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Sebastian Reichel <sre@kernel.org>,
	Matheus Castello <matheus@castello.eng.br>,
	linux-clk@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
	Michael Turquette <mturquette@baylibre.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	linux-pm@vger.kernel.org,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>,
	linux-arm-kernel@lists.infradead.org,
	Alessandro Zummo <a.zummo@towertech.it>
Subject: Re: [RFC 15/18] mfd: max77693: Do not enforce (incorrect) interrupt trigger type
Date: Mon, 21 Dec 2020 11:46:12 -0700	[thread overview]
Message-ID: <20201221184612.GA342913@robh.at.kernel.org> (raw)
In-Reply-To: <20201210212534.216197-15-krzk@kernel.org>

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@kernel.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@kernel.org>