linux-kernel - Re: [PATCH 4/4] irqchip: imgpdc: Pass on peripheral mask/unmasks to the parent

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Date:   Wed, 4 Oct 2017 15:03:02 +0100
From:   James Hogan <james.hogan@...tec.com>
To:     Ed Blake <ed.blake@...drel.com>
CC:     <tglx@...utronix.de>, <jason@...edaemon.net>,
        <marc.zyngier@....com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] irqchip: imgpdc: Pass on peripheral mask/unmasks to
 the parent

Hi Ed,

On Mon, Oct 02, 2017 at 10:55:59AM +0100, Ed Blake wrote:
> 
> Pass on peripheral (RTC/IR/WD) irq masks and unmasks to the parent
> interrupt controller, as well as setting / clearing the relevant bits
> in the IRQ_ROUTE register.
> 
> Clearing bits in the IRQ_ROUTE register will prevent future interrupts
> from being passed on to the parent, but won't mask an existing
> interrupt which has already made it to the parent.

Is it an edge or level sensitive interrupt from the PDC?

I'm a little rusty on the IRQ subsystem TBH, but if edge sensitive I
would have expected the parent interrupt to be acked/cleared by the
parent handler.

And if level sensitive I would have expected the deasserted parent
interrupt to be masked by the parent handler, and immediately cleared
upon rerouting.

Maybe you can clarify whats going on here.

Cheers
James

> This is currently
> causing peipheral interrupts to fire continuously when the system wakes
> from a suspended state when one of the peripherals is used to wake the
> system (e.g. RTC, IR).  The interrupt occurs early in the wake process
> (still in the noirq phase) and because the peripheral interrupt is
> disabled at that point, the core marks it as pending and masks it out.
> This mask must be passed to the parent controller to be effective.
> 
> Signed-off-by: Ed Blake <ed.blake@...drel.com>
> ---
>  drivers/irqchip/irq-imgpdc.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-imgpdc.c b/drivers/irqchip/irq-imgpdc.c
> index d1bcfef..05c48dd 100644
> --- a/drivers/irqchip/irq-imgpdc.c
> +++ b/drivers/irqchip/irq-imgpdc.c
> @@ -141,21 +141,31 @@ static struct pdc_intc_priv *irqd_to_priv(struct irq_data *data)
>  static void perip_irq_mask(struct irq_data *data)
>  {
>  	struct pdc_intc_priv *priv = irqd_to_priv(data);
> +	unsigned int parent_irq = priv->perip_irqs[data->hwirq];
> +	struct irq_data *parent_irq_data = irq_get_irq_data(parent_irq);
>  
>  	raw_spin_lock(&priv->lock);
>  	priv->irq_route &= ~data->mask;
>  	pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);
>  	raw_spin_unlock(&priv->lock);
> +
> +	/* Pass on the mask to the parent */
> +	parent_irq_data->chip->irq_mask(parent_irq_data);
>  }
>  
>  static void perip_irq_unmask(struct irq_data *data)
>  {
>  	struct pdc_intc_priv *priv = irqd_to_priv(data);
> +	unsigned int parent_irq = priv->perip_irqs[data->hwirq];
> +	struct irq_data *parent_irq_data = irq_get_irq_data(parent_irq);
>  
>  	raw_spin_lock(&priv->lock);
>  	priv->irq_route |= data->mask;
>  	pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);
>  	raw_spin_unlock(&priv->lock);
> +
> +	/* Pass on the unmask to the parent */
> +	parent_irq_data->chip->irq_unmask(parent_irq_data);
>  }
>  
>  static int syswake_irq_set_type(struct irq_data *data, unsigned int flow_type)
> -- 
> 1.9.1
> 

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