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leds: trigger: Load trigger modules on-demand if used as default trigger

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Even if a trigger is set as default trigger for a LED device,
the respective trigger module (if built as module) isn't automatically
loaded by the kernel if the LED device is registered. I think we can
do better. Try to load the module asynchronously by alias
ledtrig:<trigger name>. This requires that such an alias is added to
relevant triggers.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/79adb260-06ad-443a-a68e-abe4498c3298@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>
This commit is contained in:
Heiner Kallweit
2023-12-21 23:19:17 +01:00
committed by Lee Jones
parent c47d14545b
commit e09c706bfb
1 changed files with 9 additions and 0 deletions
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drivers/leds/led-triggers.c
+9
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@@ -250,6 +250,7 @@ EXPORT_SYMBOL_GPL(led_trigger_remove);
void led_trigger_set_default(struct led_classdev *led_cdev) void led_trigger_set_default(struct led_classdev *led_cdev)
{ {
struct led_trigger *trig; struct led_trigger *trig;
bool found = false;
if (!led_cdev->default_trigger) if (!led_cdev->default_trigger)
return; return;
@@ -259,6 +260,7 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
list_for_each_entry(trig, &trigger_list, next_trig) { list_for_each_entry(trig, &trigger_list, next_trig) {
if (!strcmp(led_cdev->default_trigger, trig->name) && if (!strcmp(led_cdev->default_trigger, trig->name) &&
trigger_relevant(led_cdev, trig)) { trigger_relevant(led_cdev, trig)) {
found = true;
led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER; led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
led_trigger_set(led_cdev, trig); led_trigger_set(led_cdev, trig);
break; break;
@@ -266,6 +268,13 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
} }
up_write(&led_cdev->trigger_lock); up_write(&led_cdev->trigger_lock);
up_read(&triggers_list_lock); up_read(&triggers_list_lock);
/*
* If default trigger wasn't found, maybe trigger module isn't loaded yet.
* Once loaded it will re-probe with all led_cdev's.
*/
if (!found)
request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
} }
EXPORT_SYMBOL_GPL(led_trigger_set_default); EXPORT_SYMBOL_GPL(led_trigger_set_default);