linux-kernel - Re: [PATCH RESEND 0/2] leds: gpio: Add devlink between the leds-gpio device and the gpio used.

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Message-ID: <20240220155347.693e46e1@bootlin.com>
Date: Tue, 20 Feb 2024 15:53:47 +0100
From: Herve Codina <herve.codina@...tlin.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>, Pavel Machek <pavel@....cz>,
 Lee Jones <lee@...nel.org>, Saravana Kannan <saravanak@...gle.com>,
 linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-leds@...r.kernel.org, Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH RESEND 0/2] leds: gpio: Add devlink between the
 leds-gpio device and the gpio used.

On Tue, 20 Feb 2024 15:19:57 +0100
Bartosz Golaszewski <brgl@...ev.pl> wrote:

> On Tue, Feb 20, 2024 at 2:39 PM Herve Codina <herve.codina@...tlin.com> wrote:
> >
> > Hi,
> >
> > Note: Resent this series with Saravana added in Cc.
> >
> > When a gpio used by the leds-gpio device is removed, the leds-gpio
> > device continues to use this gpio. Also, when the gpio is back, the
> > leds-gpio still uses the old removed gpio.
> >
> > A consumer/supplier relationship is missing between the leds-gpio device
> > (consumer) and the gpio used (supplier).
> >
> > This series adds an addionnal devlink between this two device.
> > With this link when the gpio is removed, the leds-gpio device is also
> > removed.
> >
> > Best regards,
> > Hervé Codina
> >
> > Herve Codina (2):
> >   gpiolib: Introduce gpiod_device_add_link()
> >   leds: gpio: Add devlinks between the gpio consumed and the gpio leds
> >     device
> >
> >  drivers/gpio/gpiolib.c        | 32 ++++++++++++++++++++++++++++++++
> >  drivers/leds/leds-gpio.c      | 15 +++++++++++++++
> >  include/linux/gpio/consumer.h |  5 +++++
> >  3 files changed, 52 insertions(+)
> >
> > --
> > 2.43.0
> >  
> 
> Can you add some more context here in the form of DT snippets that
> lead to this being needed?

/ {
	leds-dock {
		compatible = "gpio-leds";

		led-5 {
			label = "dock:alarm:red";
			gpios = <&tca6424_dock_2 12 GPIO_ACTIVE_HIGH>;
		};

		led-6 {
			label = "dock:alarm:yellow";
			gpios = <&tca6424_dock_2 13 GPIO_ACTIVE_HIGH>;
		};

		led-7 {
			label = "dock:alarm:blue";
			gpios = <&tca6424_dock_2 14 GPIO_ACTIVE_HIGH>;
		};
	};

	...
	i2c5 {
		...
		tca6424_dock_2: gpio@23 {
			compatible = "ti,tca6424";
			reg = <0x23>;
			gpio-controller;
			#gpio-cells = <2>;
			interrupt-parent = <&tca6424_dock_1>;
			interrupts = <23 IRQ_TYPE_EDGE_FALLING>;
			interrupt-controller;
			#interrupt-cells = <2>;
			vcc-supply = <&reg_dock_ctrl_3v3>;
		};
		tca6424_dock_1: gpio@22 {
			compatible = "ti,tca6424";
			reg = <0x22>;
			gpio-controller;
			#gpio-cells = <2>;
			interrupt-parent = <&gpio4>;
			interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
			interrupt-controller;
			#interrupt-cells = <2>;
			vcc-supply = <&reg_dock_ctrl_3v3>;
		};
	};
};

Also, had the exact same issue if I use a SoC gpio chip instead of an
i2c gpio expander.

Best regards,
Hervé