Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved

[Sergey Shtylyov]

Hello!

On 11.12.2021 2:45, Damien Le Moal wrote:

[...]
> > > > platform_get_irq() will print a message when it fails.
> > > > No need to repeat this.
> > > >
> > > > While at it, drop redundant check for 0 as platform_get_irq() spills
> > > > out a big WARN() in such case.
> > >
> > > The reason you should be able to remove the "if (!irq)" test is that
> > > platform_get_irq() never returns 0. At least, that is what the function kdoc
> > > says. But looking at platform_get_irq_optional(), which is called by
> > > platform_get_irq(), the out label is:
> > >
> > > 	WARN(ret == 0, "0 is an invalid IRQ number\n");
> > > 	return ret;
> > >
> > > So 0 will be returned as-is. That is rather weird. That should be fixed to
> > > return -ENXIO:
> > >
> > > 	if (WARN(ret == 0, "0 is an invalid IRQ number\n"))
> > > 		return -ENXIO;
> > > 	return ret;
> >
> >     My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this
> > but returns -EINVAL instead.
>
> Thinking more about this, shouldn't this change go into platform_get_irq()
> instead of platform_get_irq_optional() ?

   Why? platform_get_irq() currently just calls platform_get_irq_optional()...

> The way I see it, I think that the intended behavior for
> platform_get_irq_optional() is:
> 1) If have IRQ, return it, always > 0
> 2) If no IRQ, return 0

   That does include the IRQ0 case, right?

> 3) If error, return < 0
> no ?

  I completely agree, I (after thinking a bit) have no issues with that...

> And for platform_get_irq(), case (2) becomes an error.
> Is this the intended semantic ?

   I don't see how it's different from the current behavior. But we can do 
that as well, I just don't see whether it's really better...

> I am really not sure here as the functions kdoc description and the code do not
> match. Which one is correct ?

   It seems both are wrong. :-)

[...]

MBR, Sergey