Saravana needs to look at this patch too, so I am top-posting.
Yours,
Linus Walleij
On Tue, Feb 20, 2024 at 12:11 PM Herve Codina <herve.codina@xxxxxxxxxxx> wrote:
> When a gpio is removed, the gpio leds consumer need to be removed first.
> This dependency consumer/supplier can be described by devlink links.
> In case of device-tree, even if some devlinks are created due to the
> presence of gpio phandles in the gpio leds children, these links do not
> help in removing the gpio leds device (i.e. the real consumer) before
> the consumed gpio.
> We can reach cases where the gpio are no more present and the gpio leds
> driver continue to have leds using these gpio.
> Further more, when the gpio come back, the gpio leds still use the old
> removed one.
>
> Indeed, the gpio are consumed by the parent of the consumer used in the
> devlink creation due to phandles. A link is missing between the gpio and
> the real gpio consumer, the gpio leds device itself.
>
> Use the newly introduced gpiod_device_add_link() to create this
> missing link between the gpio leds devices and the gpios.
> With that done, if a gpio is removed, the gpio leds is removed and the
> resources are correctly released.
>
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> ---
> drivers/leds/leds-gpio.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
> index 83fcd7b6afff..b3ec8ecbe5da 100644
> --- a/drivers/leds/leds-gpio.c
> +++ b/drivers/leds/leds-gpio.c
> @@ -150,6 +150,7 @@ static struct gpio_leds_priv *gpio_leds_create(struct device *dev)
> {
> struct fwnode_handle *child;
> struct gpio_leds_priv *priv;
> + struct device_link *link;
> int count, ret;
>
> count = device_get_child_node_count(dev);
> @@ -197,6 +198,20 @@ static struct gpio_leds_priv *gpio_leds_create(struct device *dev)
> /* Set gpiod label to match the corresponding LED name. */
> gpiod_set_consumer_name(led_dat->gpiod,
> led_dat->cdev.dev->kobj.name);
> +
> + /*
> + * Create a link between the GPIO and the gpio-leds device.
> + * This allow to have a relationship between the gpio used and
> + * the gpio-leds device in order to automatically remove the
> + * gpio-leds device (consumer) when a GPIO (supplier) is removed.
> + */
> + link = gpiod_device_add_link(dev, led_dat->gpiod,
> + DL_FLAG_AUTOREMOVE_CONSUMER);
> + if (IS_ERR(link)) {
> + fwnode_handle_put(child);
> + return ERR_CAST(link);
> + }
> +
> priv->num_leds++;
> }
>
> --
> 2.43.0
>
