linux-kernel - Re: [PATCH v2 6/9] pinctrl: Add IRQ support to STM32 gpios

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Date:	Fri, 29 Apr 2016 10:55:03 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Mark Rutland <mark.rutland@....com>,
	Rob Herring <robh+dt@...nel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Daniel Thompson <daniel.thompson@...aro.org>,
	Bruno Herrera <bruherrera@...il.com>,
	Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH v2 6/9] pinctrl: Add IRQ support to STM32 gpios

On Fri, Apr 29, 2016 at 10:53 AM, Linus Walleij
<linus.walleij@...aro.org> wrote:
> On Tue, Apr 19, 2016 at 11:04 AM, Maxime Coquelin
> <mcoquelin.stm32@...il.com> wrote:
>> 2016-04-08 11:43 GMT+02:00 Linus Walleij <linus.walleij@...aro.org>:
>>> On Thu, Mar 31, 2016 at 5:09 PM, Maxime Coquelin
>>> <mcoquelin.stm32@...il.com> wrote:
>>>
>>>> +static int stm32_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
>>>> +{
>>>> +       struct stm32_pinctrl *pctl = dev_get_drvdata(chip->parent);
>>>> +       struct stm32_gpio_bank *bank = gpiochip_get_data(chip);
>>>> +       unsigned int irq;
>>>> +
>>>> +       regmap_field_write(pctl->irqmux[offset], bank->range.id);
>>>
>>> No. You must implement the irqchip and GPIO controllers to
>>> be orthogonal, doing things like this creates a semantic that
>>> assumes .to_irq() is always called before using the IRQ and
>>> that is not guaranteed at all. A consumer may very well
>>> use an interrupt right off the irqchip without this being called
>>> first. All this function should do is translate a number. No
>>> other semantics.
>>>
>>> This needs to be done from the irqchip (sorry).
>>
>> Actually, the register written here is not part of the irqchip.
>> It is a system config register that is only used when using a GPIO as
>> external interrupt.
>> Its aim is to mux the GPIO bank on a line.
>
> Then it should be done in .request() for the GPIO, not in
> .to_irq().
>
> It should *also* be done in the set-up path for the irqchip
> side, if that line is used without any interaction with the
> gpio side of things.

Or, hm, maybe not in the irqchip then if it is as you say
that the interrupt can be used anyway, without this being
set up.

But it should certainly not be done in .to_irq(), rather in
.request().

Yours,
Linus Walleij