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

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Date:   Mon, 7 Dec 2020 21:04:02 +0800
From:   luojiaxing <luojiaxing@...wei.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Serge Semin <fancer.lancer@...il.com>
CC:     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 2020/12/6 23:02, 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.


Yes, I agree. but in this case I mean that they will not unmasked when 
drivers request IRQ.

Drivers request IRQ will only call irq_enable(), so if we mask all IRQ 
in gpio-dwab.'s probe(),

no one will unmask the IRQ for drivers.


Thanks

Jiaxing


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