linux-kernel - Re: [PATCH v6] irqchip: Add support for tango interrupt router

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Message-ID: <a6e1fe03-56a4-0db9-ca1c-36d09936a140@free.fr>
Date:   Mon, 21 Aug 2017 18:13:07 +0200
From:   Mason <slash.tmp@...e.fr>
To:     Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>
Cc:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Mark Rutland <mark.rutland@....com>,
        Thibaud Cornic <thibaud_cornic@...madesigns.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6] irqchip: Add support for tango interrupt router

On 20/08/2017 19:22, Mason wrote:

> On 07/08/2017 14:47, Marc Zyngier wrote:
> 
>> On 01/08/17 17:56, Mason wrote:
>>
>>> +static int tango_set_type(struct irq_data *data, uint flow_type)
>>> +{
>>> +	return 0;
>>
>> What does this mean? Either you can do a set-type (and you do it), or
>> you cannot, and you fail. At least you check that what you're asked to
>> do matches the configuration.
> 
> IIRC, __irq_set_trigger() barfed when I did it differently.

The way the problem manifests is that /proc/interrupts cannot
determine the trigger types.

(I think the issue might be deeper than this cosmetic aspect.)

# cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3
 40:       1832        333       2378        471     GIC-0  29 Edge      twd
 41:        487          0          0          0    mapper   1 Edge      serial
 44:         50          0          0          0    mapper  38 Edge      eth0
 51:          3          0          0          0    mapper  37 Edge      phy_interrupt

(1 and 38 are actually level interrupts.)

	ret = sprintf(buf, "%s\n",
		      irqd_is_level_type(&desc->irq_data) ? "level" : "edge");


__irq_set_trigger() is a no-op when irq_set_type is not implemented.

But if the callback returns 0, then __irq_set_trigger() eventually calls

		irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
		irqd_set(&desc->irq_data, flags);


Should I be calling irqd_get_trigger_type() myself earlier,
perhaps in the domain alloc function?

That's what drivers/irqchip/irq-pic32-evic.c seems to do.

The comment seems to state otherwise though:
/*
 * Must only be called inside irq_chip.irq_set_type() functions.
 */
static inline void irqd_set_trigger_type(struct irq_data *d, u32 type)


Regards.