linux-kernel - Re: [PATCH 2/3] gpio: dwapb: do not create the irq mapping upfront.

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Date:	Tue, 25 Mar 2014 22:17:08 +0100
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	delicious quinoa <delicious.quinoa@...il.com>,
	Alan Tull <atull@...era.com>,
	Alexandre Courbot <gnurou@...il.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Dinh Nguyen <dinguyen@...era.com>
Subject: Re: [PATCH 2/3] gpio: dwapb: do not create the irq mapping upfront.

* Linus Walleij | 2014-03-25 21:43:49 [+0100]:

>> I looked at
>> those two links and you quote gpio_to_irq() which is not required.
>
>In a *lot* of drivers it is implicitly required that gpio_to_irq()
>is called first because they only call irq_create_mapping()
>there. (And not in subsequent interrupt handlers etc.)

so

--- a/drivers/gpio/gpio-dwapb.c
+++ b/drivers/gpio/gpio-dwapb.c
@@ -68,7 +68,7 @@ static int dwapb_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
 						    dwapb_gpio_port, bgc);
 	struct dwapb_gpio *gpio = port->gpio;
 
-	return irq_find_mapping(gpio->domain, offset);
+	return irq_create_mapping(gpio->domain, offset);
 }
 
 static void dwapb_toggle_trigger(struct dwapb_gpio *gpio, unsigned int offs)

would fix the problem then. That means you get the gpio number passed as
a value and you plan to use it as an irq via gpio_to_irq() and the
latter will create the interrupt mapping then.

>No matter what, I would worry less about that and spend
>some time on using my new gpiolib helpers for
>gpiochip_irqchip_add() and
>gpiochip_set_chained_irqchip().
>
>Yours,
>Linus Walleij

Sebastian
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