From: Andy Shevchenko <andriy.shevchenko@linux•intel.com>
To: Geert Uytterhoeven <geert@linux-m68k•org>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix•de>,
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Subject: Re: [PATCH 1/2] platform: make platform_get_irq_optional() optional
Date: Wed, 12 Jan 2022 14:27:58 +0200 [thread overview]
Message-ID: <Yd7JTvfblG0Ge4AN@smile.fi.intel.com> (raw)
In-Reply-To: <CAMuHMdWsMGPiQaPS0-PJ_+Mc5VQ37YdLfbHr_aS40kB+SfW-aw@mail.gmail.com>
On Wed, Jan 12, 2022 at 11:27:02AM +0100, Geert Uytterhoeven wrote:
> On Wed, Jan 12, 2022 at 9:51 AM Uwe Kleine-König
> <u.kleine-koenig@pengutronix•de> wrote:
> > On Wed, Jan 12, 2022 at 09:33:48AM +0100, Geert Uytterhoeven wrote:
> > > On Mon, Jan 10, 2022 at 10:20 PM Andrew Lunn <andrew@lunn•ch> wrote:
> > > > On Mon, Jan 10, 2022 at 09:10:14PM +0100, Uwe Kleine-König wrote:
> > > > > On Mon, Jan 10, 2022 at 10:54:48PM +0300, Sergey Shtylyov wrote:
> > > > > > This patch is based on the former Andy Shevchenko's patch:
> > > > > >
> > > > > > https://lore.kernel.org/lkml/20210331144526.19439-1-andriy.shevchenko@linux.intel.com/
> > > > > >
> > > > > > Currently platform_get_irq_optional() returns an error code even if IRQ
> > > > > > resource simply has not been found. It prevents the callers from being
> > > > > > error code agnostic in their error handling:
> > > > > >
> > > > > > ret = platform_get_irq_optional(...);
> > > > > > if (ret < 0 && ret != -ENXIO)
> > > > > > return ret; // respect deferred probe
> > > > > > if (ret > 0)
> > > > > > ...we get an IRQ...
> > > > > >
> > > > > > All other *_optional() APIs seem to return 0 or NULL in case an optional
> > > > > > resource is not available. Let's follow this good example, so that the
> > > > > > callers would look like:
> > > > > >
> > > > > > ret = platform_get_irq_optional(...);
> > > > > > if (ret < 0)
> > > > > > return ret;
> > > > > > if (ret > 0)
> > > > > > ...we get an IRQ...
> > > > >
> > > > > The difference to gpiod_get_optional (and most other *_optional) is that
> > > > > you can use the NULL value as if it were a valid GPIO.
> > > > >
> > > > > As this isn't given with for irqs, I don't think changing the return
> > > > > value has much sense.
> > > >
> > > > We actually want platform_get_irq_optional() to look different to all
> > > > the other _optional() methods because it is not equivalent. If it
> > > > looks the same, developers will assume it is the same, and get
> > > > themselves into trouble.
> > >
> > > Developers already assume it is the same, and thus forget they have
> > > to check against -ENXIO instead of zero.
> >
> > Is this an ack for renaming platform_get_irq_optional() to
> > platform_get_irq_silent()?
>
> No it isn't ;-)
>
> If an optional IRQ is not present, drivers either just ignore it (e.g.
> for devices that can have multiple interrupts or a single muxed IRQ),
> or they have to resort to polling. For the latter, fall-back handling
> is needed elsewhere in the driver.
> To me it sounds much more logical for the driver to check if an
> optional irq is non-zero (available) or zero (not available), than to
> sprinkle around checks for -ENXIO. In addition, you have to remember
> that this one returns -ENXIO, while other APIs use -ENOENT or -ENOSYS
> (or some other error code) to indicate absence. I thought not having
> to care about the actual error code was the main reason behind the
> introduction of the *_optional() APIs.
For the record, I'm on the same page with Geert.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2022-01-12 12:29 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20220110195449.12448-1-s.shtylyov@omp.ru>
2022-01-10 19:54 ` [PATCH 1/2] platform: make platform_get_irq_optional() optional Sergey Shtylyov
2022-01-10 20:10 ` Uwe Kleine-König
2022-01-10 21:07 ` Andy Shevchenko
2022-01-10 21:44 ` Uwe Kleine-König
2022-01-10 21:18 ` Andrew Lunn
2022-01-12 8:33 ` Geert Uytterhoeven
2022-01-12 8:50 ` Uwe Kleine-König
2022-01-12 10:27 ` Geert Uytterhoeven
2022-01-12 12:27 ` Andy Shevchenko [this message]
2022-01-12 13:38 ` Andrew Lunn
2022-01-12 13:51 ` Andy Shevchenko
2022-01-12 13:54 ` Geert Uytterhoeven
2022-01-12 14:41 ` Rafael J. Wysocki
2022-01-12 15:05 ` Sergey Shtylyov
2022-01-12 15:13 ` Hans de Goede
2022-01-12 15:48 ` Rafael J. Wysocki
2022-01-12 16:21 ` Andy Shevchenko
2022-01-12 21:31 ` Uwe Kleine-König
2022-01-12 21:45 ` Mark Brown
2022-01-13 11:08 ` Uwe Kleine-König
2022-01-13 14:45 ` Mark Brown
2022-01-13 19:43 ` [PATCH] driver core: platform: Rename platform_get_irq_optional() to platform_get_irq_silent() Uwe Kleine-König
2022-01-13 20:17 ` Mark Brown
2022-01-13 20:57 ` Sergey Shtylyov
2022-01-13 22:43 ` Uwe Kleine-König
2022-01-14 9:58 ` Geert Uytterhoeven
2022-01-15 15:21 ` Uwe Kleine-König
2022-01-15 21:06 ` Sergey Shtylyov
2022-01-14 11:34 ` Sergey Shtylyov
2022-01-13 20:31 ` Guenter Roeck
2022-01-13 21:42 ` Florian Fainelli
2022-01-13 23:06 ` Uwe Kleine-König
2022-01-14 17:55 ` Sergey Shtylyov
2022-01-15 13:55 ` Uwe Kleine-König
2022-01-19 18:36 ` Andy Shevchenko
2022-01-19 19:44 ` Sergey Shtylyov
2022-01-19 18:40 ` Andy Shevchenko
2022-01-14 6:57 ` Peter Korsgaard
2022-01-14 13:04 ` Andy Shevchenko
2022-01-15 15:45 ` Uwe Kleine-König
2022-01-19 18:51 ` Andy Shevchenko
2022-01-19 19:47 ` Sergey Shtylyov
2022-01-19 20:55 ` Andy Shevchenko
2022-01-20 7:57 ` Uwe Kleine-König
2022-01-24 15:01 ` Andy Shevchenko
2022-01-24 21:02 ` Sergey Shtylyov
2022-01-25 8:25 ` Geert Uytterhoeven
2022-01-25 12:56 ` Matthias Schiffer
2022-01-25 14:01 ` Andy Shevchenko
2022-01-14 19:45 ` Sergey Shtylyov
2022-01-14 20:29 ` Uwe Kleine-König
2022-01-15 13:08 ` Sergey Shtylyov
2022-01-19 18:52 ` Andy Shevchenko
2022-01-13 20:35 ` [PATCH 1/2] platform: make platform_get_irq_optional() optional Sergey Shtylyov
2022-01-14 9:25 ` Uwe Kleine-König
2022-01-14 9:39 ` Geert Uytterhoeven
2022-01-14 19:14 ` Sergey Shtylyov
2022-01-14 20:22 ` Uwe Kleine-König
2022-01-15 20:22 ` Sergey Shtylyov
2022-01-17 8:41 ` Geert Uytterhoeven
2022-01-17 9:24 ` Uwe Kleine-König
2022-01-17 10:35 ` Geert Uytterhoeven
2022-01-17 11:49 ` Uwe Kleine-König
2022-01-17 13:08 ` Geert Uytterhoeven
2022-01-17 17:06 ` Uwe Kleine-König
2022-01-18 8:25 ` Geert Uytterhoeven
2022-01-18 9:09 ` Uwe Kleine-König
2022-01-18 9:37 ` Geert Uytterhoeven
2022-01-18 12:08 ` Uwe Kleine-König
2022-01-18 12:49 ` Geert Uytterhoeven
2022-01-18 14:29 ` Uwe Kleine-König
2022-01-19 16:12 ` Sergey Shtylyov
2022-01-19 18:29 ` Sergey Shtylyov
2022-01-20 11:27 ` Sergey Shtylyov
2022-01-16 18:15 ` Sergey Shtylyov
2022-01-17 8:47 ` Uwe Kleine-König
2022-01-18 20:21 ` Sergey Shtylyov
2022-01-18 22:26 ` Uwe Kleine-König
2022-01-19 15:34 ` Sergey Shtylyov
2022-01-19 18:58 ` Andy Shevchenko
2022-01-19 19:49 ` Sergey Shtylyov
2022-01-14 18:46 ` Sergey Shtylyov
2022-01-15 18:36 ` [PATCH 1/2] platform: make platform_get_irq_optional() optional (summary) Uwe Kleine-König
2022-01-16 14:19 ` Greg Kroah-Hartman
2022-01-18 9:18 ` Uwe Kleine-König
2022-01-18 9:32 ` Greg Kroah-Hartman
2022-01-19 10:56 ` Sergey Shtylyov
2022-01-19 11:33 ` Uwe Kleine-König
2022-01-19 11:42 ` Sergey Shtylyov
2022-01-19 19:06 ` Andy Shevchenko
2022-01-17 11:57 ` [PATCH 1/2] platform: make platform_get_irq_optional() optional Sergey Shtylyov
2022-01-19 15:02 ` Uwe Kleine-König
2022-01-19 15:50 ` Sergey Shtylyov
2022-01-10 19:54 ` [PATCH 2/2] platform: make platform_get_irq_byname_optional() optional Sergey Shtylyov
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