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leds: core: Report ENODATA for brightness of hardware controlled LED

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While the LED is controlled fully by the hardware, the value cached by
the LED driver core is incorrect. Return ENODATA to userspace in this
case.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20260521-cros_ec-leds-hw-trigger-brightness-v1-1-6cd9d7c9671e@weissschuh.net
Signed-off-by: Lee Jones <lee@kernel.org>
This commit is contained in:
Thomas Weißschuh
2026-05-21 18:42:41 +02:00
committed by Lee Jones
parent 8f040b5c5e
commit b819dc7d8f
1 changed files with 13 additions and 0 deletions
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13
drivers/leds/led-class.c
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@@ -27,12 +27,25 @@ static LIST_HEAD(leds_lookup_list);
static struct workqueue_struct *leds_wq;
static bool led_trigger_is_hw_controlled(struct led_classdev *led_cdev)
{
#ifdef CONFIG_LEDS_TRIGGERS
guard(rwsem_read)(&led_cdev->trigger_lock);
return led_cdev->trigger && led_cdev->trigger->trigger_type;
#else
return false;
#endif
}
static ssize_t brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
unsigned int brightness;
if (led_trigger_is_hw_controlled(led_cdev))
return -ENODATA;
mutex_lock(&led_cdev->led_access);
led_update_brightness(led_cdev);
brightness = led_cdev->brightness;