This allows to setup ordered workqueue for leds events. This may be
useful, because default 'system_wq' does not guarantee execution order
of each work_struct, thus for several brightness update requests (for
multiple leds), real brightness switch could be in random order.
Yes, for sysfs-based leds we have flush_work() call inside
brightness_store() operation, but it's blocking call, so userspace
caller can be blocked at a long time, which means leds animation stream
can be broken.
Ordered workqueue has the same behaviour as system_wq + flush_work(),
but all scheduled works are async and userspace caller is not blocked,
which it better for userspace animation scheduling.
Signed-off-by: Alexey Romanov <avromanov@xxxxxxxxxxxxxxxxx>
Signed-off-by: Dmitry Rokosov <ddrokosov@xxxxxxxxxxxxxxxxx>
---
drivers/leds/led-class.c | 12 +++++++++++-
drivers/leds/led-core.c | 6 +++---
include/linux/leds.h | 1 +
3 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index ba1be15cfd8e..fba12471cf1f 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -25,6 +25,8 @@
static DEFINE_MUTEX(leds_lookup_lock);
static LIST_HEAD(leds_lookup_list);
+static struct workqueue_struct *leds_wq;
+
static ssize_t brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -57,7 +59,6 @@ static ssize_t brightness_store(struct device *dev,
if (state == LED_OFF)
led_trigger_remove(led_cdev);
led_set_brightness(led_cdev, state);
- flush_work(&led_cdev->set_brightness_work);
ret = size;
unlock:
@@ -549,6 +550,8 @@ int led_classdev_register_ext(struct device *parent,
led_update_brightness(led_cdev);
+ led_cdev->wq = leds_wq;
+
led_init_core(led_cdev);
#ifdef CONFIG_LEDS_TRIGGERS
@@ -667,12 +670,19 @@ EXPORT_SYMBOL_GPL(devm_led_classdev_unregister);
static int __init leds_init(void)
{
+ leds_wq = alloc_ordered_workqueue("leds", 0);
+ if (!leds_wq) {
+ pr_err("failed to create leds ordered workqueue\n");
+ return -ENOMEM;
+ }
+
return class_register(&leds_class);
}
static void __exit leds_exit(void)
{
class_unregister(&leds_class);
+ destroy_workqueue(leds_wq);
}
subsys_initcall(leds_init);
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 89c9806cc97f..9769ac49be20 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -266,7 +266,7 @@ void led_blink_set_nosleep(struct led_classdev *led_cdev, unsigned long delay_on
led_cdev->delayed_delay_on = delay_on;
led_cdev->delayed_delay_off = delay_off;
set_bit(LED_SET_BLINK, &led_cdev->work_flags);
- schedule_work(&led_cdev->set_brightness_work);
+ queue_work(led_cdev->wq, &led_cdev->set_brightness_work);
return;
}
@@ -297,7 +297,7 @@ void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness)
*/
if (!brightness) {
set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
- schedule_work(&led_cdev->set_brightness_work);
+ queue_work(led_cdev->wq, &led_cdev->set_brightness_work);
} else {
set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
&led_cdev->work_flags);
@@ -333,7 +333,7 @@ void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value)
set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags);
}
- schedule_work(&led_cdev->set_brightness_work);
+ queue_work(led_cdev->wq, &led_cdev->set_brightness_work);
}
EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 6300313c46b7..7c9f1cb12ab9 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -169,6 +169,7 @@ struct led_classdev {
int new_blink_brightness;
void (*flash_resume)(struct led_classdev *led_cdev);
+ struct workqueue_struct *wq; /* LED workqueue */
struct work_struct set_brightness_work;
int delayed_set_value;
unsigned long delayed_delay_on;
--
2.43.0
