@@ -209,6 +209,19 @@ static int led_bl_probe(struct platform_device *pdev)
return PTR_ERR(priv->bl_dev);
}
+ for (i = 0; i < priv->nb_leds; i++) {
+ struct device_link *link;
+
+ link = device_link_add(&pdev->dev, priv->leds[0]->dev->parent,
+ DL_FLAG_AUTOREMOVE_CONSUMER);
+ if (!link) {
+ dev_err(&pdev->dev, "Failed to add devlink (consumer %s, supplier %s)\n",
+ dev_name(&pdev->dev), dev_name(priv->leds[0]->dev->parent));
+ backlight_device_unregister(priv->bl_dev);
+ return -EINVAL;
+ }
+ }
+
for (i = 0; i < priv->nb_leds; i++) {
mutex_lock(&priv->leds[i]->led_access);
led_sysfs_disable(priv->leds[i]);
led-backlight is a consumer of one or multiple LED class devices, but devlink is currently unable to create correct supplier-producer links when the supplier is a class device. One consequence is that removal order is not correctly enforced. Issues happen for example with the following sections in a device tree overlay: // An LED driver chip pca9632@62 { compatible = "nxp,pca9632"; reg = <0x62>; // ... addon_led_pwm: led-pwm@3 { reg = <3>; label = "addon:led:pwm"; }; }; backlight-addon { compatible = "led-backlight"; leds = <&addon_led_pwm>; brightness-levels = <255>; default-brightness-level = <255>; }; On removal of the above overlay, the LED driver can be removed before the backlight device, resulting in: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 ... Call trace: led_put+0xe0/0x140 devm_led_release+0x6c/0x98 Another way to reproduce the bug without any device tree overlays is unbinding the LED class device (pca9632@62) before unbinding the consumer (backlight-addon): echo 11-0062 >/sys/bus/i2c/drivers/leds-pca963x/unbind echo ...backlight-dock >/sys/bus/platform/drivers/led-backlight/unbind Fix by adding a devlink between the consuming led-backlight device and the supplying LED device, as other drivers and subsystems do as well. Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> Fixes: ae232e45acf9 ("backlight: add led-backlight driver") Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> --- Changes in v5: - separated this patch as a standalone patch - improved commit message, adding feedback from Alexander - no code changes This patch first appeared in the v4 of a longer series, even though the issue is orthogonal: https://lore.kernel.org/all/20240917-hotplug-drm-bridge-v4-6-bc4dfee61be6@bootlin.com/ --- drivers/video/backlight/led_bl.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21 change-id: 20250519-led-backlight-add-devlink-to-supplier-class-device-6dec4e04445a Best regards,