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

[Raag Jadav]

On Mon, May 19, 2025 at 01:44:49PM +0300, Andy Shevchenko wrote:
> On Fri, May 16, 2025 at 10:20:02PM +0300, Raag Jadav wrote:
> > 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:
> 
> ...
> 
> > > > > > +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.
> 
> To make get_resource() work, someone has to add those resources to the list.
> The question is, why do we need this for AUX devices? Are you expecting
> several IRQs to be dedicated for several devices (no sharing)? If now, why
> is the fwnode version of IRQ getter not enough?

With PCI type MFDs, MSIX would be a fair possibility, if not now atleast
in the future.

> > Please correct me if I've misunderstood your question.
> 
> For the memory and port resources it might be indeed needed to have a split.
> But then, since it's a lot of the copy from platform code, I would expect
> the common library for both rather than reinventing the wheel. To achieve
> that one might need to abstract away from the certain device container when
> handling resources (no platform_device nor auxiliary_device). Would that
> approach work?

Sure, let me explore this. Thanks for the suggestions.

Raag