led-backlight is a consumer of one or multiple LED class devices, but no
devlink is created for such supplier-producer relationship. One consequence
is that removal ordered 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
Fix by adding a devlink between the consuming led-backlight device and the
supplying LED device.
Signed-off-by: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx>
---
This patch first appeared in v4.
---
drivers/video/backlight/led_bl.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c
index c7aefcd6e4e3..bfbd80728036 100644
--- a/drivers/video/backlight/led_bl.c
+++ b/drivers/video/backlight/led_bl.c
@@ -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]);
--
2.34.1
