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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 25 Jan 2022 09:25:25 +0100
Message-ID: <CAMuHMdXouECKa43OwUgQ6dA+gNeOqEZHZgOmQzqknzYiA924YA@mail.gmail.com>
Subject: Re: [PATCH] driver core: platform: Rename platform_get_irq_optional()
 to platform_get_irq_silent()
To:     Sergey Shtylyov <s.shtylyov@omp.ru>
Cc:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
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Hi Sergey,

On Mon, Jan 24, 2022 at 10:02 PM Sergey Shtylyov <s.shtylyov@omp.ru> wrote:
> On 1/24/22 6:01 PM, Andy Shevchenko wrote:
> >>>>>>> It'd certainly be good to name anything that doesn't correspond to one
> >>>>>>> of the existing semantics for the API (!) something different rather
> >>>>>>> than adding yet another potentially overloaded meaning.
> >>>>>>
> >>>>>> It seems we're (at least) three who agree about this. Here is a patch
> >>>>>> fixing the name.
> >>>>>
> >>>>> And similar number of people are on the other side.
> >>>>
> >>>> If someone already opposed to the renaming (and not only the name) I
> >>>> must have missed that.
> >>>>
> >>>> So you think it's a good idea to keep the name
> >>>> platform_get_irq_optional() despite the "not found" value returned by it
> >>>> isn't usable as if it were a normal irq number?
> >>>
> >>> I meant that on the other side people who are in favour of Sergey's patch.
> >>> Since that I commented already that I opposed the renaming being a standalone
> >>> change.
> >>>
> >>> Do you agree that we have several issues with platform_get_irq*() APIs?
> [...]
> >>> 2. The vIRQ0 handling: a) WARN() followed by b) returned value 0
> >>
> >> I'm happy with the vIRQ0 handling. Today platform_get_irq() and it's
> >> silent variant returns either a valid and usuable irq number or a
> >> negative error value. That's totally fine.
> >
> > It might return 0.
> > Actually it seems that the WARN() can only be issued in two cases:
> > - SPARC with vIRQ0 in one of the array member
> > - fallback to ACPI for GPIO IRQ resource with index 0
>
>    You have probably missed the recent discovery that arch/sh/boards/board-aps4*.c
> causes IRQ0 to be passed as a direct IRQ resource?

So far no one reported seeing the big fat warning ;-)

> > The bottom line here is the SPARC case. Anybody familiar with the platform
> > can shed a light on this. If there is no such case, we may remove warning
> > along with ret = 0 case from platfrom_get_irq().
>
>    I'm afraid you're too fast here... :-)
>    We'll have a really hard time if we continue to allow IRQ0 to be returned by
> platform_get_irq() -- we'll have oto fileter it out in the callers then...

So far no one reported seeing the big fat warning?

> >>> 3. The specific cookie for "IRQ not found, while no error happened" case
> >>
> >> Not sure what you mean here. I have no problem that a situation I can
> >> cope with is called an error for the query function. I just do error
> >> handling and continue happily. So the part "while no error happened" is
> >> irrelevant to me.
> >
> > I meant that instead of using special error code, 0 is very much good for
> > the cases when IRQ is not found. It allows to distinguish -ENXIO from the
> > low layer from -ENXIO with this magic meaning.
>
>    I don't see how -ENXIO can trickle from the lower layers, frankly...

It might one day, leading to very hard to track bugs.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds