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

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Message-ID: <ZGpS-13CozLp-p4f@surfacebook>
Date:   Sun, 21 May 2023 20:20:59 +0300
From:   andy.shevchenko@...il.com
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>,
        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

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.


-- 
With Best Regards,
Andy Shevchenko