netdev - [PATCH v4 7/7] iio: cdc: ad7150: Functional change

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Date: Tue, 16 May 2023 10:14:10 +0300
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>,
	Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Daniel Scally <djrscally@...il.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Andreas Klinger <ak@...klinger.de>, Marcin Wojtas <mw@...ihalf.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jonathan Neuschäfer <j.neuschaefer@....net>,
	Linus Walleij <linus.walleij@...aro.org>,
	Paul Cercueil <paul@...pouillou.net>, Wolfram Sang <wsa@...nel.org>,
	Akhil R <akhilrajeev@...dia.com>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	netdev@...r.kernel.org, openbmc@...ts.ozlabs.org,
	linux-gpio@...r.kernel.org, linux-mips@...r.kernel.org
Subject: [PATCH v4 7/7] iio: cdc: ad7150: Functional change

fwnode_irq_get[_byname]() were changed to not return 0 anymore. The
special error case where device-tree based IRQ mapping fails can't no
longer be reliably detected from this return value. This yields a
functional change in the driver where the mapping failure is treated as
an error.

The mapping failure can occur for example when the device-tree IRQ
information translation call-back(s) (xlate) fail, IRQ domain is not
found, IRQ type conflicts, etc. In most cases this indicates an error in
the device-tree and special handling is not really required.

One more thing to note is that ACPI APIs do not return zero for any
failures so this special handling did only apply on device-tree based
systems.

Drop the special handling for DT mapping failures as these can no longer
be separated from other errors at driver side.

Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>

---

Please note that I don't have the hardware to test this change.
Furthermore, testing this type of device-tree error cases is not
trivial, as the question we probably dive in is "what happens with the
existing users who have errors in the device-tree". Answering to this
question is not simple.

I did this patch with minimal code changes - but a question is if we
should really jump into the else branch below on all IRQ getting errors?

        } else {
                indio_dev->info = &ad7150_info_no_irq;
                switch (id->driver_data) {
                case AD7150:
                        indio_dev->channels = ad7150_channels_no_irq;
                        indio_dev->num_channels =
                                ARRAY_SIZE(ad7150_channels_no_irq);
                        break;
                case AD7151:
                        indio_dev->channels = ad7151_channels_no_irq;
                        indio_dev->num_channels =
                                ARRAY_SIZE(ad7151_channels_no_irq);
                        break;
                default:
                        return -EINVAL;
                }

Why do we have special handling for !chip->interrupts[0] while other
errors on getting the fwnode_irq_get(dev_fwnode(&client->dev), 0); will
abort the probe?

The first patch of the series changes the fwnode_irq_get() so this depends
on the first patch of the series and should not be applied alone.
---
 drivers/iio/cdc/ad7150.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/iio/cdc/ad7150.c b/drivers/iio/cdc/ad7150.c
index 79aeb0aaea67..d7ba50b9780d 100644
--- a/drivers/iio/cdc/ad7150.c
+++ b/drivers/iio/cdc/ad7150.c
@@ -567,8 +567,7 @@ static int ad7150_probe(struct i2c_client *client)
 		if (chip->interrupts[1] < 0)
 			return chip->interrupts[1];
 	}
-	if (chip->interrupts[0] &&
-	    (id->driver_data == AD7151 || chip->interrupts[1])) {
+	if (id->driver_data == AD7151 || chip->interrupts[1]) {
 		irq_set_status_flags(chip->interrupts[0], IRQ_NOAUTOEN);
 		ret = devm_request_threaded_irq(&client->dev,
 						chip->interrupts[0],
-- 
2.40.1

-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 

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