linux-kernel - Re: [PATCH v1 09/43] clocksource: ep93xx: Add driver for Cirrus Logic EP93xx

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Date:   Thu, 29 Jun 2023 16:39:19 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Nikita Shubin <nikita.shubin@...uefel.me>
Cc:     Alexander Sverdlin <alexander.sverdlin@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Michael Peters <mpeters@...eddedts.com>,
        Kris Bahnsen <kris@...eddedts.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 09/43] clocksource: ep93xx: Add driver for Cirrus Logic EP93xx

On Thu, Jun 29, 2023 at 4:10 PM Nikita Shubin <nikita.shubin@...uefel.me> wrote:
> On Wed, 2023-06-21 at 11:28 +0300, Andy Shevchenko wrote:
> > On Wed, Jun 21, 2023 at 11:22 AM Nikita Shubin
> > <nikita.shubin@...uefel.me> wrote:

...

> > > > > +       irq = irq_of_parse_and_map(np, 0);
> > > > > +       if (irq <= 0) {
> > > > > +               pr_err("ERROR: invalid interrupt number\n");
> > > > > +               ret = -EINVAL;
> > > >
> > > > Shadowed error in case of negative returned code. Why?
> > >
> > > Majority of clocksource drivers shadow it. Same like above.
> >
> > It doesn't mean they are correct or using brand new APIs.
>
> Or may be this because irq_of_parse_and_map can return zero as error,
> and returning zero from timer_init means success ?
>
> Please correct me if i am wrong here.

0 means no mapped IRQ.

> > Can you use fwnode_irq_get() instead?
>
> Will it help ?

Yes, definitely, in two aspects:
1/ it makes code less OF-dependent (helps also OF people to clean up
the spread of OF headers and APIs where they are not needed);
2/ it takes care about proper error codes.

-- 
With Best Regards,
Andy Shevchenko