linux-kernel - "leds: gpio: Use generic support for composing LED names" breaks gpio debugfs

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Message-ID: <20191204110219.GV25745@shell.armlinux.org.uk>
Date:   Wed, 4 Dec 2019 11:02:19 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Pavel Machek <pavel@....cz>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: "leds: gpio: Use generic support for composing LED names" breaks
 gpio debugfs

Hi,

Patch d7235f5feaa0 ("leds: gpio: Use generic support for composing LED
names") changed the way labels are used.

devm_fwnode_get_gpiod_from_child() is passed led.name, which used to be
set to the label or node name, resulting in /sys/kernel/debug/gpio
containing useful information.  For example:

 gpio-487 (                    |udpu:green:power    ) out lo
 gpio-488 (                    |udpu:red:power      ) out hi
 gpio-489 (                    |udpu:green:network  ) out hi
 gpio-490 (                    |udpu:red:network    ) out hi
 gpio-491 (                    |udpu:green:alarm    ) out hi
 gpio-492 (                    |udpu:red:alarm      ) out hi

After this commit, it now contains a rather less useful:

 gpio-487 (                    |?                   ) out hi ACTIVE LOW
 gpio-488 (                    |?                   ) out hi ACTIVE LOW
 gpio-489 (                    |?                   ) out hi ACTIVE LOW
 gpio-490 (                    |?                   ) out hi ACTIVE LOW
 gpio-491 (                    |?                   ) out hi ACTIVE LOW
 gpio-492 (                    |?                   ) out hi ACTIVE LOW

This is because led.name is now NULL prior to the call to
devm_fwnode_get_gpiod_from_child().

While this is not an API, it is useful for debugging, and given the
dynamic allocation of GPIOs to physical GPIOs, having the labels
present is an advantage.

Can this be fixed / old behaviour restored?

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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