linux-kernel - Re: [PATCH v5 1/2] driver core: auxiliary bus: Introduce auxiliary device resource management

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Message-ID: <aCeP4l1VOVfhtQ09@black.fi.intel.com>
Date: Fri, 16 May 2025 22:20:02 +0300
From: Raag Jadav <raag.jadav@...el.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: gregkh@...uxfoundation.org, david.m.ertman@...el.com,
	ira.weiny@...el.com, lee@...nel.org,
	mika.westerberg@...ux.intel.com, heikki.krogerus@...ux.intel.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] driver core: auxiliary bus: Introduce auxiliary
 device resource management

On Thu, May 15, 2025 at 04:06:47PM +0300, Andy Shevchenko wrote:
> On Thu, May 15, 2025 at 03:52:38PM +0300, Raag Jadav wrote:
> > On Wed, May 14, 2025 at 03:36:49PM +0300, Andy Shevchenko wrote:
> > > On Wed, May 14, 2025 at 05:54:31PM +0530, Raag Jadav wrote:
> 
> ...
> 
> > > > +/**
> > > > + * auxiliary_get_irq_optional - get an optional IRQ for auxiliary device
> > > > + * @auxdev: auxiliary device
> > > > + * @num: IRQ number index
> > > > + *
> > > > + * Gets an IRQ for a auxiliary device. Device drivers should check the return value
> > > > + * for errors so as to not pass a negative integer value to the request_irq()
> > > > + * APIs. This is the same as auxiliary_get_irq(), except that it does not print an
> > > > + * error message if an IRQ can not be obtained.
> > > > + *
> > > > + * For example::
> > > > + *
> > > > + *		int irq = auxiliary_get_irq_optional(auxdev, 0);
> > > > + *		if (irq < 0)
> > > > + *			return irq;
> > > > + *
> > > > + * Return: non-zero IRQ number on success, negative error number on failure.
> > > > + */
> > > > +int auxiliary_get_irq_optional(struct auxiliary_device *auxdev, unsigned int num)
> > > > +{
> > > > +	struct resource *r;
> > > > +	int ret = -ENXIO;
> > > > +
> > > > +	r = auxiliary_get_resource(auxdev, IORESOURCE_IRQ, num);
> > > > +	if (!r)
> > > > +		goto out;
> > > > +
> > > > +	/*
> > > > +	 * The resources may pass trigger flags to the irqs that need to be
> > > > +	 * set up. It so happens that the trigger flags for IORESOURCE_BITS
> > > > +	 * correspond 1-to-1 to the IRQF_TRIGGER* settings.
> > > > +	 */
> > > > +	if (r->flags & IORESOURCE_BITS) {
> > > > +		struct irq_data *irqd;
> > > > +
> > > > +		irqd = irq_get_irq_data(r->start);
> > > > +		if (!irqd)
> > > > +			goto out;
> > > > +		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
> > > > +	}
> > > > +
> > > > +	ret = r->start;
> > > > +	if (WARN(!ret, "0 is an invalid IRQ number\n"))
> > > > +		ret = -EINVAL;
> > > > +out:
> > > > +	return ret;
> > > > +}
> > > 
> > > Please, do not inherit the issues that the respective platform device API has.
> > > And after all, why do you need this? What's wrong with plain fwnode_irq_get()?
> > 
> > Can you please elaborate? Are we expecting fwnode to be supported by auxiliary
> > device?
> 
> Platform IRQ getter is legacy for the board files, but it has support for fwnode.
> Why do you need to inherit all that legacy? What's the point?

This is just to abstract get_resource(IRQ) which has been carved up by the
parent device. And since this is an auxiliary child device, I'm not sure if
we have a firmware to work with.

Please correct me if I've misunderstood your question.

Raag