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

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Date: Tue, 20 Feb 2024 16:30:11 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Herve Codina <herve.codina@...tlin.com>
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, Feb 20, 2024 at 3:53 PM Herve Codina <herve.codina@...tlin.com> wrote:
>
> 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>;
>                 };

Do I understand correctly that the devlink is created between "led-5"
and "tca6424_dock_2" but actually should also be created between
"leds-dock" and "tca6424_dock_2"?

Bartosz

>
>                 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