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

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Date:   Mon, 7 Dec 2020 21:10:24 +0800
From:   luojiaxing <luojiaxing@...wei.com>
To:     Marc Zyngier <maz@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     Serge Semin <fancer.lancer@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        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>, Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it


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.


Thanks

Jiaxing


>
> Thanks,
>
>         M.