From: Thomas Gleixner <tglx@linutronix.de>
To: Serge Semin <fancer.lancer@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Luo Jiaxing <luojiaxing@huawei.com>,
Marc Zyngier <maz@kernel.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Serge Semin <Sergey.Semin@baikalelectronics.ru>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linuxarm <linuxarm@huawei.com>
Subject: Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it
Date: Fri, 15 Dec 2023 11:56:02 +0100 [thread overview]
Message-ID: <87a5qbohtp.ffs@tglx> (raw)
In-Reply-To: <cbgdeksaulqu65nbnz7l4wpuwensllkdlyi5babhpngclze4df@zxetbohgpfvg>
On Fri, Dec 15 2023 at 13:24, Serge Semin wrote:
> On Fri, Dec 15, 2023 at 09:09:09AM +0100, Thomas Gleixner wrote:
>> On Sat, Dec 05 2020 at 22:58, Linus Walleij wrote:
>> > Sorry for top posting but I need the help of the irqchip maintainer
>> > Marc Z to hash this out.
>> >
>> > The mask/unmask/disable/enable semantics is something that
>> > you need to work with every day to understand right.
>>
>> The patch is correct.
>>
>> The irq_enable() callback is required to be a superset of
>> irq_unmask(). I.e. the core code expects it to do:
>>
>> 1) Some preparatory work to enable the interrupt line
>>
>> 2) Unmask the interrupt, which is why the masked state is cleared
>> by the core after invoking the irq_enable() callback.
>>
>> #2 is pretty obvious because if an interrupt chip does not implement the
>> irq_enable() callback the core defaults to irq_unmask()
>>
>> Correspondingly the core expects from the irq_disable() callback:
>>
>> 1) To mask the interrupt
>>
>> 2) To do some extra work to disable the interrupt line
>>
>> Same reasoning as above vs. #1 as the core fallback is to invoke the
>> irq_unmask() callback when the irq_disable() callback is not
>> implemented.
>
> Just curious. Wouldn't that be more correct/portable for the core to
> call both callbacks when it's required and if both are provided? So
> the supersetness requirement would be no longer applied to the
> IRQ enable/disable callbacks implementation thus avoiding the code
> duplications in the low-level drivers.
We could do that, but there are chips which require atomicity of the
operations (#1/#2). Not sure whether it safes much.
Thanks,
tglx
next prev parent reply other threads:[~2023-12-15 10:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 9:36 [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it Luo Jiaxing
2020-11-30 11:22 ` Andy Shevchenko
2020-12-01 8:59 ` luojiaxing
2020-12-05 22:15 ` Serge Semin
2020-12-06 15:02 ` Linus Walleij
2020-12-06 18:50 ` Marc Zyngier
2020-12-07 13:10 ` luojiaxing
2021-01-06 10:24 ` Bartosz Golaszewski
[not found] ` <CAHp75VcFo2hc1kjP9jLxmCdN79rD2R4vCw2P8UssbWe2v4zwcw@mail.gmail.com>
2021-01-07 12:20 ` Serge Semin
2020-12-07 13:04 ` luojiaxing
2020-12-07 12:44 ` luojiaxing
2020-12-05 21:58 ` Linus Walleij
2023-12-15 8:09 ` Thomas Gleixner
2023-12-15 10:24 ` Serge Semin
2023-12-15 10:56 ` Thomas Gleixner [this message]
2023-12-15 12:57 ` Serge Semin
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