linux-kernel - Re: [PATCH] mfd: cottula: add cottula board

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Date:	Mon, 15 Dec 2014 16:45:03 +0100
From:	Robert Jarzmik <robert.jarzmik@...e.fr>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH] mfd: cottula: add cottula board

Arnd Bergmann <arnd@...db.de> writes:

> On Monday 15 December 2014 00:10:06 Robert Jarzmik wrote:
>> +
>> +       platform_set_drvdata(pdev, cot);
>> +       cot->gpio0 = gpiod_get(&pdev->dev, "lubbock_irq", 0);
>> +       if (IS_ERR(cot->gpio0)) {
>> +               dev_err(&pdev->dev, "Couldn't request GPIO : ret = %d\n", ret);
>> +               return PTR_ERR(cot->gpio0);
>> +       }
>> +       cot->irq = gpiod_to_irq(cot->gpio0);
>> +       if (cot->irq < 0)
>> +               return cot->irq;
>> +
>> +       cot->irqdomain =
>> +               irq_domain_add_linear(pdev->dev.of_node, COTTULA_NB_IRQ,
>> +                                     &cottula_irq_domain_ops, cot);
>> +       if (!cot->irqdomain)
>> +               return -ENODEV;
>> +
>> +       ret = 0;
>> +       if (base_irq)
>> +               ret = irq_create_strict_mappings(cot->irqdomain, base_irq, 0,
>> +                                                COTTULA_NB_IRQ);
>> 
>
> This looks a bit ambiguous: You get a GPIO line for the purpose of the
> IRQ nesting but don't use the GPIO otherwise, and you pass the device's
> own irq domain start as an IORESOURCE_IRQ resource.
>
> For consistency between DT and ATAGS based uses, and with similar DT
> based drivers, I would instead recommend passing the parent irq (from
> the GPIO) as an IORESOURCE_IRQ resource instead of a gpio lookup,
> and passing the base_irq as platform_data for the ATAGS case.

I understand Arnd, yet I wanted to avoid any platform data if possible, as this
is a motherboard, it will not be plugged anywhere else with different
parameters.

What would you say if I did this :
 - remove the gpio
 - use IORESOURCE_IRQ(0) as the parent irq (as you suggested)
 - use IORESOURCE_IRQ(1) as the base_irq
   => this resource would be optional
        - if exists, use it as base_irq
        - if doesn't exist, let base_irq = 0

Will that look correct ?

Cheers.

-- 
Robert
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