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From: Stephen Warren <swarren@wwwdotorg.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Linus Walleij <linus.walleij@stericsson.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Stephen Warren <swarren@nvidia.com>,
	Anmar Oueja <anmar.oueja@linaro.org>,
	Lee Jones <lee.jones@linaro.org>
Subject: Re: [PATCH] pinctrl/nomadik: use irq_create_mapping()
Date: Mon, 22 Oct 2012 14:08:42 -0600	[thread overview]
Message-ID: <5085A7CA.3070001@wwwdotorg.org> (raw)
In-Reply-To: <CACRpkdbcTT_Mfa67Vw_6Y3RvqOE3CMA7kNXLG5oja0uTNn1FoA@mail.gmail.com>

On 10/22/2012 02:14 AM, Linus Walleij wrote:
> On Fri, Oct 19, 2012 at 6:22 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 10/19/2012 09:09 AM, Linus Walleij wrote:
>>> From: Linus Walleij <linus.walleij@linaro.org>
>>
>>> @@ -931,7 +931,7 @@ static void __nmk_gpio_irq_handler(unsigned int irq, struct irq_desc *desc,
>>>       while (status) {
>>>               int bit = __ffs(status);
>>>
>>> -             generic_handle_irq(irq_find_mapping(nmk_chip->domain, bit));
>>> +             generic_handle_irq(irq_create_mapping(nmk_chip->domain, bit));
>>
>> Surely this one can remain as irq_find_mapping() since isn't
>> nmk_gpio_to_irq() guaranteed to have been called first for this GPIO/IRQ?
> 
> It's an IRQ handler so it should be robust to spurious IRQs due to
> transient hardware states etc I believe.
> 
> So if there is a transient IRQ before gpio_to_irq() is called -> boom.

I wonder though (a) why it would be unmasked in HW, and (b) why the
software would even look at the status bit if no handler were registered?


WARNING: multiple messages have this Message-ID (diff)
From: swarren@wwwdotorg.org (Stephen Warren)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] pinctrl/nomadik: use irq_create_mapping()
Date: Mon, 22 Oct 2012 14:08:42 -0600	[thread overview]
Message-ID: <5085A7CA.3070001@wwwdotorg.org> (raw)
In-Reply-To: <CACRpkdbcTT_Mfa67Vw_6Y3RvqOE3CMA7kNXLG5oja0uTNn1FoA@mail.gmail.com>

On 10/22/2012 02:14 AM, Linus Walleij wrote:
> On Fri, Oct 19, 2012 at 6:22 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 10/19/2012 09:09 AM, Linus Walleij wrote:
>>> From: Linus Walleij <linus.walleij@linaro.org>
>>
>>> @@ -931,7 +931,7 @@ static void __nmk_gpio_irq_handler(unsigned int irq, struct irq_desc *desc,
>>>       while (status) {
>>>               int bit = __ffs(status);
>>>
>>> -             generic_handle_irq(irq_find_mapping(nmk_chip->domain, bit));
>>> +             generic_handle_irq(irq_create_mapping(nmk_chip->domain, bit));
>>
>> Surely this one can remain as irq_find_mapping() since isn't
>> nmk_gpio_to_irq() guaranteed to have been called first for this GPIO/IRQ?
> 
> It's an IRQ handler so it should be robust to spurious IRQs due to
> transient hardware states etc I believe.
> 
> So if there is a transient IRQ before gpio_to_irq() is called -> boom.

I wonder though (a) why it would be unmasked in HW, and (b) why the
software would even look at the status bit if no handler were registered?

  reply	other threads:[~2012-10-22 20:08 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-19 15:09 [PATCH] pinctrl/nomadik: use irq_create_mapping() Linus Walleij
2012-10-19 15:09 ` Linus Walleij
2012-10-19 16:22 ` Stephen Warren
2012-10-19 16:22   ` Stephen Warren
2012-10-22  8:14   ` Linus Walleij
2012-10-22  8:14     ` Linus Walleij
2012-10-22 20:08     ` Stephen Warren [this message]
2012-10-22 20:08       ` Stephen Warren
2012-10-23  8:31       ` Linus Walleij
2012-10-23  8:31         ` Linus Walleij

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