linux-kernel - Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it

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Message-ID: <CACRpkdawv2NUahn2gniH=29T6qqqFYSa53giC01PS1wq91+Ksg@mail.gmail.com>
Date:   Sun, 6 Dec 2020 16:02:30 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Serge Semin <fancer.lancer@...il.com>
Cc:     luojiaxing <luojiaxing@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it

On Sat, Dec 5, 2020 at 11:15 PM Serge Semin <fancer.lancer@...il.com> wrote:

> Hmm, that sounds like a problem, but the explanation is a bit unclear
> to me. AFAICS you are saying that the only callbacks which are
> called during the IRQ request/release are the irq_enable(), right? If
> so then the only reason why we haven't got a problem reported due to
> that so far is that the IRQs actually unmasked by default.

What we usually do in cases like that (and I have discussed this
with tglx in the past I think) is to simply mask off all IRQs in probe().
Then they will be unmasked when requested by drivers.

See e.g. gpio-pl061 that has this line in probe():
writeb(0, pl061->base + GPIOIE); /* disable irqs */

Yours,
Linus Walleij