linux-kernel - Re: [PATCH 1/2] gpio: pcf857x: Propagate wake-up setting to parent irq controller

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Date:	Tue, 13 Jan 2015 15:26:49 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Geert Uytterhoeven <geert+renesas@...der.be>
Cc:	Alexandre Courbot <gnurou@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Ingo Molnar <mingo@...hat.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] gpio: pcf857x: Propagate wake-up setting to parent
 irq controller

On Wed, Dec 10, 2014 at 2:36 PM, Geert Uytterhoeven
<geert+renesas@...der.be> wrote:

> The pcf857x GPIO and interrupt controller uses dummy_irq_chip, which
> does not implement irq_chip.irq_set_wake() and does not set
> IRQCHIP_SKIP_SET_WAKE.
>
> This causes two s2ram issues if wake-up is enabled for the pcf857x GPIO
> pins:
>   1. During resume from s2ram, the following warning is printed:
>
>      WARNING: CPU: 0 PID: 1046 at kernel/irq/manage.c:537 irq_set_irq_wake+0x9c/0xf8()
>      Unbalanced IRQ 113 wake disable
>
>   2. Wake-up through the pcf857x GPIO pins may fail, as the parent
>      interrupt controller may be suspended.
>
> Migrate the pcf857x GPIO and interrupt controller from dummy_irq_chip to
> its own irq_chip. This irq chip implements irq_chip.irq_set_wake() to
> propagate its wake-up setting to the parent interrupt controller.
>
> This fixes wake-up through gpio-keys on sh73a0/kzm9g, where the pcf857x
> interrupt is cascaded to irq-renesas-intc-irqpin, and the latter must
> not be suspended when wake-up is enabled.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
(...)
> +static struct irq_chip pcf857x_irq_chip = {
> +       .name           = "pcf857x",
> +       .irq_startup    = noop_ret,
> +       .irq_shutdown   = noop,
> +       .irq_enable     = noop,
> +       .irq_disable    = noop,
> +       .irq_ack        = noop,
> +       .irq_mask       = noop,
> +       .irq_unmask     = noop,
> +       .irq_set_wake   = pcf857x_irq_set_wake,
> +};

Argh this is so simplistic ... any GPIO irqchip worthy of it's name
shoult at least call gpiochip_lock_as_irq() in .irq_request_resources() and vice
versa mutatis mutandis in .irq_release_resources().

Isn't it possible to also migrate this to GPIOLIB_IRQCHIP when
you're at it can also cut out a big chunk of rusty code?

Yours,
Linus Walleij
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