linux-kernel - Re: [PATCH] pinctrl: ingenic: Convert to immutable irq chip

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Date:   Thu, 09 Jun 2022 11:00:44 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Aidan MacDonald <aidanmacdonald.0x0@...il.com>
Cc:     linus.walleij@...aro.org, linux-mips@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl: ingenic: Convert to immutable irq chip

Hi Aidan,

Le mar., juin 7 2022 at 17:47:19 +0100, Aidan MacDonald 
<aidanmacdonald.0x0@...il.com> a écrit :
> 
> Paul Cercueil <paul@...pouillou.net> writes:
> 
>>  Hi Aidan,
>> 
>>  Le mar., juin 7 2022 at 12:05:25 +0100, Aidan MacDonald
>>  <aidanmacdonald.0x0@...il.com> a écrit :
>>>  Update the driver to use an immutable IRQ chip to fix this warning:
>>>      "not an immutable chip, please consider fixing it!"
>>>  Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@...il.com>
>>>  ---
>>>   drivers/pinctrl/pinctrl-ingenic.c | 33 
>>> ++++++++++++++++++-------------
>>>   1 file changed, 19 insertions(+), 14 deletions(-)
>>>  diff --git a/drivers/pinctrl/pinctrl-ingenic.c
>>>  b/drivers/pinctrl/pinctrl-ingenic.c
>>>  index 1ca11616db74..37258fb05be3 100644
>>>  --- a/drivers/pinctrl/pinctrl-ingenic.c
>>>  +++ b/drivers/pinctrl/pinctrl-ingenic.c
>>>  @@ -135,7 +135,6 @@ struct ingenic_pinctrl {
>>>   struct ingenic_gpio_chip {
>>>   	struct ingenic_pinctrl *jzpc;
>>>   	struct gpio_chip gc;
>>>  -	struct irq_chip irq_chip;
>>>   	unsigned int irq, reg_base;
>>>   };
>>>  @@ -3419,6 +3418,8 @@ static void ingenic_gpio_irq_enable(struct 
>>> irq_data
>>>  *irqd)
>>>   	struct ingenic_gpio_chip *jzgc = gpiochip_get_data(gc);
>>>   	int irq = irqd->hwirq;
>>>  +	gpiochip_enable_irq(gc, irq);
>>>  +
>>>   	if (is_soc_or_above(jzgc->jzpc, ID_JZ4770))
>>>   		ingenic_gpio_set_bit(jzgc, JZ4770_GPIO_INT, irq, true);
>>>   	else if (is_soc_or_above(jzgc->jzpc, ID_JZ4740))
>>>  @@ -3443,6 +3444,8 @@ static void ingenic_gpio_irq_disable(struct 
>>> irq_data
>>>  *irqd)
>>>   		ingenic_gpio_set_bit(jzgc, JZ4740_GPIO_SELECT, irq, false);
>>>   	else
>>>   		ingenic_gpio_set_bit(jzgc, JZ4730_GPIO_GPIER, irq, false);
>>>  +
>>>  +	gpiochip_disable_irq(gc, irq);
>>>   }
>>>   static void ingenic_gpio_irq_ack(struct irq_data *irqd)
>>>  @@ -3684,6 +3687,20 @@ static void ingenic_gpio_irq_release(struct 
>>> irq_data
>>>  *data)
>>>   	return gpiochip_relres_irq(gpio_chip, data->hwirq);
>>>   }
>>>  +static const struct irq_chip ingenic_gpio_irqchip = {
>>>  +	.name			= "gpio",
>>>  +	.irq_enable		= ingenic_gpio_irq_enable,
>>>  +	.irq_disable		= ingenic_gpio_irq_disable,
>>>  +	.irq_unmask		= ingenic_gpio_irq_unmask,
>>>  +	.irq_mask		= ingenic_gpio_irq_mask,
>>>  +	.irq_ack		= ingenic_gpio_irq_ack,
>>>  +	.irq_set_type		= ingenic_gpio_irq_set_type,
>>>  +	.irq_set_wake		= ingenic_gpio_irq_set_wake,
>>>  +	.irq_request_resources	= ingenic_gpio_irq_request,
>>>  +	.irq_release_resources	= ingenic_gpio_irq_release,
>>>  +	.flags			= IRQCHIP_MASK_ON_SUSPEND | IRQCHIP_IMMUTABLE,
>>>  +};
>>>  +
>>>   static int ingenic_pinmux_set_pin_fn(struct ingenic_pinctrl *jzpc,
>>>   		int pin, int func)
>>>   {
>>>  @@ -4172,20 +4189,8 @@ static int __init ingenic_gpio_probe(struct
>>>  ingenic_pinctrl *jzpc,
>>>   	if (!jzgc->irq)
>>>   		return -EINVAL;
>>>  -	jzgc->irq_chip.name = jzgc->gc.label;
>>>  -	jzgc->irq_chip.irq_enable = ingenic_gpio_irq_enable;
>>>  -	jzgc->irq_chip.irq_disable = ingenic_gpio_irq_disable;
>>>  -	jzgc->irq_chip.irq_unmask = ingenic_gpio_irq_unmask;
>>>  -	jzgc->irq_chip.irq_mask = ingenic_gpio_irq_mask;
>>>  -	jzgc->irq_chip.irq_ack = ingenic_gpio_irq_ack;
>>>  -	jzgc->irq_chip.irq_set_type = ingenic_gpio_irq_set_type;
>>>  -	jzgc->irq_chip.irq_set_wake = ingenic_gpio_irq_set_wake;
>>>  -	jzgc->irq_chip.irq_request_resources = ingenic_gpio_irq_request;
>>>  -	jzgc->irq_chip.irq_release_resources = ingenic_gpio_irq_release;
>>>  -	jzgc->irq_chip.flags = IRQCHIP_MASK_ON_SUSPEND;
>>>  -
>>>   	girq = &jzgc->gc.irq;
>>>  -	girq->chip = &jzgc->irq_chip;
>>>  +	gpio_irq_chip_set_chip(girq, &ingenic_gpio_irqchip);
>> 
>>  This will change each irq_chip's name to "gpio", do we want that?
>> 
>>  You didn't remove jzgc->irq_chip, so maybe what you could do is
>>  jzgc->irq_chip = ingenic_gpio_irqchip;
>>  jzgc->irq_chip.name = jzgc->gc.label;
>>  gpio_irq_chip_set_chip(girq, &jzgc->irq_chip);
>> 
>>  Thoughts?
>> 
>>  Cheers,
>>  -Paul
>> 
> 
> I wondered that myself, but it doesn't seem to affect anything except
> what is displayed in /proc/interrupts. Is the name used anywhere else
> where it might cause confusion?

I don't really know. If it only really affects the display in 
/proc/interrupts then I'm fine with it. In doubt, I'd prefer to keep 
the existing names.

> The only similar case I could find was pinctrl-microchip-sgpio.c where
> microchip_sgpio_register_bank() is called in a loop and registers the
> same irq chip repeatedly, so it's probably(?) okay to do this here. It
> seems to defeat the point of immutable irqchips if they just have to 
> be
> copied anyway...

The point of immutable irqchips is that they aren't modified by the 
core, if I understand it correctly. Immutable doesn't mean it has to be 
static const.

> (btw, I did remove jzgc->irq_chip -- or did I miss something?)

Oops, missed that.

Cheers,
-Paul

> Best regards,
> Aidan
> 
>>>   	girq->parent_handler = ingenic_gpio_irq_handler;
>>>   	girq->num_parents = 1;
>>>   	girq->parents = devm_kcalloc(dev, 1, sizeof(*girq->parents),
>>>  --
>>>  2.35.1
>>> 
>