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

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Date:   Wed, 6 Jan 2021 11:24:11 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     luojiaxing <luojiaxing@...wei.com>
Cc:     Marc Zyngier <maz@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Serge Semin <fancer.lancer@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it

On Mon, Dec 7, 2020 at 2:10 PM luojiaxing <luojiaxing@...wei.com> wrote:
>
>
> On 2020/12/7 2:50, Marc Zyngier wrote:
> > On 2020-12-06 15:02, Linus Walleij wrote:
> >> 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 */
> >
> > This should definitely be the default behaviour. The code code
> > expects all interrupt sources to be masked until actively enabled,
> > usually with the IRQ being requested.
>
>
> I think this patch is used for that purpose. I do two things in
> irq_enable(): unmask irq and then enable IRQ;
>
> and for irq_disable(), it's similar; mask IRQ then disable it.

Hi!

Could you please resend this patch rebased on top of v5.11-rc2 and
with the detailed explanation you responded with to Andy as part of
the commit message?

Thanks!
Bart