linux-kernel - Re: [PATCH v5 4/8] pinctrl: wpcm450: relax return value check for IRQ get

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Message-ID: <44c87ed5-f14d-e690-1e5f-74212370611b@gmail.com>
Date:   Mon, 22 May 2023 08:16:32 +0300
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     andy.shevchenko@...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>,
        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>,
        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 v5 4/8] pinctrl: wpcm450: relax return value check for IRQ
 get

On 5/21/23 20:20, andy.shevchenko@...il.com wrote:
> Fri, May 19, 2023 at 02:02:16PM +0300, Matti Vaittinen kirjoitti:
>> 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 (no error, just skip the IRQ) handling for DT mapping
>> failures as these can no longer be separated from other errors at driver
>> side.
> 
> ...
> 
>> 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 :)
> 
> No need to repeat this. As I answered the case c) was in my mind when I made
> that change.

True. I'll drop that if I re-spin. Thanks for pointing it out.


Yours,
	-- Matti

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

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