linux-kernel - Re: [PATCH v4 4/7] pinctrl: wpcm450: elax return value check for IRQ get

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Message-ID: <61e12f46-a283-3e12-5f5c-5086a3c1bb35@fi.rohmeurope.com>
Date:   Wed, 17 May 2023 05:41:57 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     Jonathan Neuschäfer <j.neuschaefer@....net>,
        Matti Vaittinen <mazziesaccount@...il.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>,
        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-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>
Subject: Re: [PATCH v4 4/7] pinctrl: wpcm450: elax return value check for IRQ
 get

Thanks for taking a look at this Jonathan.

On 5/16/23 19:32, Jonathan Neuschäfer wrote:
> Hello,
> 
>> [PATCH v4 4/7] pinctrl: wpcm450: elax return value check for IRQ get
> 
> Typo ("elax") in the subject line.

It mut've ben the leter eatng moster :)

I'll take care of this when re-spinning.

> On Tue, May 16, 2023 at 10:13:14AM +0300, Matti Vaittinen wrote:
>> The special handling in this driver was added when fixing a problem
>> where returning zero from fwnode_irq_get[_byname]() was treated as
>> succes yielding zero being used as a valid IRQ by the driver.
>> f4a31facfa80 ("pinctrl: wpcm450: Correct the fwnode_irq_get() return value check")
>> The commit message does not mention if choosing not to abort the probe
>> on device-tree mapping failure (as is done on other errors) was chosen
>> because: a) Abort would have broken some existing setup. b) Because skipping
>> an IRQ on failure is "the right thing to do", or c) because it sounded like
>> a way to minimize risk of breaking something.
>>
>> If the reason is a) - then I'd appreciate receiving some more
>> information and a suggestion how to proceed (if possible). If the reason
>> is b), then it might be best to just skip the IRQ instead of aborting
>> the probe for all errors on IRQ getting. Finally, in case of c), well,
>> by acking this change you will now accept the risk :)
>>
>> 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.
> 
> Thanks for investigating this!
> 
> It's not a), because there are no existing setups that rely on broken
> IRQs connected to this pinctrl/GPIO controller.

Glad to know. Then we should be able to "unify" the error handling no 
matter what fails when IRQ is tried to be obtained. Either by always 
aborting the probe or by skipping the broken IRQs.

> I suspect b) or c), but I'll let Andy give a more definite answer.
> 
>> ---
>>   drivers/pinctrl/nuvoton/pinctrl-wpcm450.c | 2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/pinctrl/nuvoton/pinctrl-wpcm450.c b/drivers/pinctrl/nuvoton/pinctrl-wpcm450.c
>> index 2d1c1652cfd9..f9326210b5eb 100644
>> --- a/drivers/pinctrl/nuvoton/pinctrl-wpcm450.c
>> +++ b/drivers/pinctrl/nuvoton/pinctrl-wpcm450.c
>> @@ -1106,8 +1106,6 @@ static int wpcm450_gpio_register(struct platform_device *pdev,
>>   			irq = fwnode_irq_get(child, i);
>>   			if (irq < 0)
>>   				break;
>> -			if (!irq)
>> -				continue;
>>   
>>   			girq->parents[i] = irq;
>>   			girq->num_parents++;
> 
> Anyway, this looks good to me.
> 
> Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@....net>

Yours,
	-- Matti

-- 
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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