linux-kernel - Re: [PATCH V1 08/15] spmi: pmic_arb: use appropriate flow handler

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Date:   Wed, 31 May 2017 12:03:10 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Kiran Gunda <kgunda@...eaurora.org>
Cc:     Abhijeet Dharmapurikar <adharmap@...eaurora.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        David Collins <collinsd@...eaurora.org>,
        Subbaraman Narayanamurthy <subbaram@...eaurora.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        adharmap@...cinc.com, aghayal@....qualcomm.com
Subject: Re: [PATCH V1 08/15] spmi: pmic_arb: use appropriate flow handler

On 05/30, Kiran Gunda wrote:
> From: Abhijeet Dharmapurikar <adharmap@...eaurora.org>
> 
> The current code uses handle_level_irq flow handler even if the
> trigger type of the interrupt is edge. This can lead to missing
> of an edge transition that happens when the interrupt is being
> handled. The level flow handler masks the interrupt while it is
> being handled, so if an edge transition happens at that time,
> that edge is lost.
> 
> Use an edge flow handler for edge type interrupts which ensures
> that the interrupt stays enabled while being handled - at least
> until it triggers at which point the flow handler sets the
> IRQF_PENDING flag and only then masks the interrupt. That
> IRQF_PENDING state indicates an edge transition happened while
> the interrupt was being handled and the handler is called again.
> 
> Signed-off-by: Abhijeet Dharmapurikar <adharmap@...eaurora.org>
> Signed-off-by: Kiran Gunda <kgunda@...eaurora.org>

Do we have any edge interrupts in the tree right now? At least
RTC seems to be using edge... This should go back to stable with
a Fixes tag.

> ---
>  drivers/spmi/spmi-pmic-arb.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
> index 1d23df0..ad34491 100644
> --- a/drivers/spmi/spmi-pmic-arb.c
> +++ b/drivers/spmi/spmi-pmic-arb.c
> @@ -625,6 +625,12 @@ static int qpnpint_irq_set_type(struct irq_data *d, unsigned int flow_type)
>  	}
>  
>  	qpnpint_spmi_write(d, QPNPINT_REG_SET_TYPE, &type, sizeof(type));
> +
> +	if (flow_type & IRQ_TYPE_EDGE_BOTH)

IRQ_TYPE_EDGE_BOTH doesn't seem appropriate to use here. We're
really just testing to see if the type is an edge type, not if
it's BOTH edges.

> +		irq_set_handler_locked(d, handle_edge_irq);
> +	else
> +		irq_set_handler_locked(d, handle_level_irq);
> +

And we already have code that does that check:

	if (flow_type & (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING))

so just put the irq_set_handler_locked() calls in those if
statements please.

-- 
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