linux-kernel - Re: [PATCH] gpio: mvebu: clear irq in edge cause register before unmask edge irq

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Message-ID: <CACRpkdbefJsH2km3p433NN2koNck7hgNqLWpD3q4r=Um75GZEw@mail.gmail.com>
Date:   Wed, 15 Jan 2020 14:26:43 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Maxim <bigunclemax@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        linux-pwm@...r.kernel.org,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpio: mvebu: clear irq in edge cause register before
 unmask edge irq

On Wed, Jan 15, 2020 at 8:40 AM Maxim <bigunclemax@...il.com> wrote:

> From: Maxim Kiselev <bigunclemax@...il.com>
>
> When input GPIO set from 0 to 1, the interrupt bit asserted in the GPIO
> Interrupt Cause Register (ICR) even if the corresponding interrupt
> masked in the GPIO Interrupt Mask Register.
>
> Because interrupt mask register only affects assertion of the interrupt
> bits in Main Interrupt Cause Register and it does not affect the
> setting of bits in the GPIO ICR.
>
> So, there is problem, when we unmask interrupt with already
> asserted bit in the GPIO ICR, then false interrupt immediately occurs
> even if GPIO don't change their value since last unmask.
>
> Signed-off-by: Maxim Kiselev <bigunclemax@...il.com>

This looks correct to me, a review from the MVEBU maintainers
would be appreciated.

- Should it be applied to fixes as a regression fix?

- Should it be tagged for stable?

Yours.
Linus Walleij