linux-kernel - Re: [PATCH v2] gpio: pcf857x: handle only enabled irqs

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Date:	Tue, 16 Jun 2015 13:52:17 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Linus Walleij <linus.walleij@...aro.org>
CC:	Alexandre Courbot <gnurou@...il.com>, Sekhar Nori <nsekhar@...com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>
Subject: Re: [PATCH v2] gpio: pcf857x: handle only enabled irqs

On 06/16/2015 12:06 PM, Geert Uytterhoeven wrote:
> On Tue, Jun 16, 2015 at 10:58 AM, Linus Walleij
> <linus.walleij@...aro.org> wrote:
>> <grygorii.strashko@...com> wrote:
>>
>>> Now pcf857x_irq() IRQ's dispatcher will try to run nested
>>> IRQ handlers for each GPIO pin which state has changed.
>>> Such IRQs are, actually, spurious and nested IRQ handlers
>>> have to be called only for IRQs wich were enabled by users.
>>> This is not critical issue - just  /proc/interrupts
>>> will display counters for unused IRQS:
>>> 399:          4          0   pcf857x   0 Edge
>>> 428:          1          0   pcf857x  13 Edge
>>> 430:          1          0   pcf857x  15 Edge
>>>
>>> Hence, fix it by adding irq_enabled field in struct pcf857x to track
>>> enabled GPIO IRQs and corresponding callbacks in pcf857x_irq_chip.
>>>
>>> Similar functionality was presented in pcf857x driver, commit
>>> 21fd3cd1874a ('gpio: pcf857x: call the gpio user handler iff...')
>>>
>>> and then it was removed by commit
>>>   a39294bdf4b0 ('gpio: pcf857x: Switch to use gpiolib irqchip...')
>>>
>>> Cc: Geert Uytterhoeven <geert+renesas@...der.be>
>>>
>>> Fixes: a39294bdf4b0 ('gpio: pcf857x: Switch to use gpiolib irqchip helpers')
>>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>>> ---
>>>
>>> No functional changes.
>>> It's just rebased on top of "devel" branch
>>> git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git
>>
>> Patch applied since no comments arrived.

Thanks.

> 
> Sorry for the late reply, still recovering from travel backlog.
> I gave it a quick try on sh73a0/kzm9g. No visible impact, gpio keys and
> wake-up from s2ram still work.

Thanks.

> 
> Note that this board didn't seem to be affected by the issue that was fixed by
> 21fd3cd1874a ('gpio: pcf857x: call the gpio user handler iff...').

True. This is because generic_handle_irq() is not used any more, and  handle_nested_irq()
is used instead. So, original issue, fixed by 21fd3cd1874a,
transformed into  displaying of wrong IRQ statistic which is fixed by this patch.

-- 
regards,
-grygorii
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