leds: leds-pwm: Defer led_pwm_set() if PWM can sleep

Call to led_pwm_set() can happen inside atomic context, like triggers.
If the PWM call can sleep, defer using a worker.

Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index a1ea5f6..faf52c0 100644 (file)
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -23,12 +23,16 @@
 #include <linux/pwm.h>
 #include <linux/leds_pwm.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 
 struct led_pwm_data {
        struct led_classdev     cdev;
        struct pwm_device       *pwm;
+       struct work_struct      work;
        unsigned int            active_low;
        unsigned int            period;
+       int                     duty;
+       bool                    can_sleep;
 };
 
 struct led_pwm_priv {
@@ -36,6 +40,26 @@ struct led_pwm_priv {
        struct led_pwm_data leds[0];
 };
 
+static void __led_pwm_set(struct led_pwm_data *led_dat)
+{
+       int new_duty = led_dat->duty;
+
+       pwm_config(led_dat->pwm, new_duty, led_dat->period);
+
+       if (new_duty == 0)
+               pwm_disable(led_dat->pwm);
+       else
+               pwm_enable(led_dat->pwm);
+}
+
+static void led_pwm_work(struct work_struct *work)
+{
+       struct led_pwm_data *led_dat =
+               container_of(work, struct led_pwm_data, work);
+
+       __led_pwm_set(led_dat);
+}
+
 static void led_pwm_set(struct led_classdev *led_cdev,
        enum led_brightness brightness)
 {
@@ -44,13 +68,12 @@ static void led_pwm_set(struct led_classdev *led_cdev,
        unsigned int max = led_dat->cdev.max_brightness;
        unsigned int period =  led_dat->period;
 
-       if (brightness == 0) {
-               pwm_config(led_dat->pwm, 0, period);
-               pwm_disable(led_dat->pwm);
-       } else {
-               pwm_config(led_dat->pwm, brightness * period / max, period);
-               pwm_enable(led_dat->pwm);
-       }
+       led_dat->duty = brightness * period / max;
+
+       if (led_dat->can_sleep)
+               schedule_work(&led_dat->work);
+       else
+               __led_pwm_set(led_dat);
 }
 
 static inline size_t sizeof_pwm_leds_priv(int num_leds)
@@ -100,6 +123,10 @@ static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
                led_dat->cdev.brightness = LED_OFF;
                led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 
+               led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
+               if (led_dat->can_sleep)
+                       INIT_WORK(&led_dat->work, led_pwm_work);
+
                ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
                if (ret < 0) {
                        dev_err(&pdev->dev, "failed to register for %s\n",
@@ -153,6 +180,10 @@ static int led_pwm_probe(struct platform_device *pdev)
                        led_dat->cdev.max_brightness = cur_led->max_brightness;
                        led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 
+                       led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
+                       if (led_dat->can_sleep)
+                               INIT_WORK(&led_dat->work, led_pwm_work);
+
                        ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
                        if (ret < 0)
                                goto err;
@@ -180,8 +211,11 @@ static int led_pwm_remove(struct platform_device *pdev)
        struct led_pwm_priv *priv = platform_get_drvdata(pdev);
        int i;
 
-       for (i = 0; i < priv->num_leds; i++)
+       for (i = 0; i < priv->num_leds; i++) {
                led_classdev_unregister(&priv->leds[i].cdev);
+               if (priv->leds[i].can_sleep)
+                       cancel_work_sync(&priv->leds[i].work);
+       }
 
        return 0;
 }