linux-kernel - Re: [PATCH v2 4/4] irqchip: sun4i: Use handle_fasteoi_late

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Message-ID: <alpine.DEB.2.02.1403131542060.18573@ionos.tec.linutronix.de>
Date:	Thu, 13 Mar 2014 15:46:26 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Hans de Goede <hdegoede@...hat.com>
cc:	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org,
	devicetree <devicetree@...r.kernel.org>,
	linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 4/4] irqchip: sun4i: Use handle_fasteoi_late_irq for
 the ENMI (irq 0)

On Wed, 12 Mar 2014, Hans de Goede wrote:

> The ENMI needs to have the ack done *after* clearing the interrupt source,
> otherwise we will get a spurious interrupt for each real interrupt. Switch
> to the new handle_fasteoi_late_irq handler which gives us the desired behavior.
> 
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
>  drivers/irqchip/irq-sun4i.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-sun4i.c b/drivers/irqchip/irq-sun4i.c
> index 8a2fbee..4b1c874 100644
> --- a/drivers/irqchip/irq-sun4i.c
> +++ b/drivers/irqchip/irq-sun4i.c
> @@ -77,15 +77,22 @@ static void sun4i_irq_unmask(struct irq_data *irqd)
>  static struct irq_chip sun4i_irq_chip = {
>  	.name		= "sun4i_irq",
>  	.irq_ack	= sun4i_irq_ack,
> +	.irq_eoi	= sun4i_irq_ack, /* For the ENMI */
>  	.irq_mask	= sun4i_irq_mask,
>  	.irq_unmask	= sun4i_irq_unmask,
> +	.flags		= IRQCHIP_EOI_THREADED, /* Only affects the ENMI */

That's not really true. The flags affect all interrupts which share
that chip.

>  };
>  
>  static int sun4i_irq_map(struct irq_domain *d, unsigned int virq,
>  			 irq_hw_number_t hw)
>  {
> -	irq_set_chip_and_handler(virq, &sun4i_irq_chip,
> -				 handle_level_irq);
> +	if (hw == 0) /* IRQ 0, the ENMI needs special handling */
> +		irq_set_chip_and_handler(virq, &sun4i_irq_chip,
> +					 handle_fasteoi_late_irq);
> +	else
> +		irq_set_chip_and_handler(virq, &sun4i_irq_chip,
> +					 handle_level_irq);

I wonder what happens when you use the fasteoi handler for all of
them.

Thanks,

	tglx
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