linux-kernel - Re: [PATCH v6 8/8] i2c: i2c-smbus: fwnode_irq_get

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Date:   Sun, 28 May 2023 18:09:13 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Matti Vaittinen <mazziesaccount@...il.com>
Cc:     Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        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>,
        Wolfram Sang <wsa@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        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>,
        Akhil R <akhilrajeev@...dia.com>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...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: Re: [PATCH v6 8/8] i2c: i2c-smbus: fwnode_irq_get_byname() return
 value fix

On Fri, 26 May 2023 09:39:37 +0300
Matti Vaittinen <mazziesaccount@...il.com> wrote:

> The fwnode_irq_get_byname() was changed to not return 0 upon failure so
> return value check can be adjusted to reflect the change.
> 
> Reviewed-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
> 

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

Comments follow though...
> ---
> Revision history:
> v5 =>:
>  - No changes
> v4 => v5:
>  - Added back after this was accidentally dropped at v4.
> 
> Depends on the mentioned return value change which is in patch 1/2. The

1/8?  Or just use 1/N and you never have to update it.

> return value change does also cause a functional change here. Eg. when
> IRQ mapping fails, the fwnode_irq_get_byname() no longer returns zero.
> This will cause also the probe here to return nonzero failure. I guess
> this is desired behaviour - but I would appreciate any confirmation.
> 
> Please, see also previous discussion here:
> https://lore.kernel.org/all/fbd52f5f5253b382b8d7b3e8046134de29f965b8.1666710197.git.mazziesaccount@gmail.com/
> 
> Another suggestion has been to drop the check altogether. I am slightly
> reluctant on doing that unless it gets confirmed that is the "right
> thing to do".

I'd be more inclined to also fail in the setup->irq < 0 path and drop the later check
on basis I can't see the driver doing anything useful wtihout an interrupt.

> ---
>  drivers/i2c/i2c-smbus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
> index 138c3f5e0093..893fe7cd3e41 100644
> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c
> @@ -129,7 +129,7 @@ static int smbalert_probe(struct i2c_client *ara)
>  	} else {
>  		irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),
>  					    "smbus_alert");
> -		if (irq <= 0)
> +		if (irq < 0)
>  			return irq;
>  	}
>