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>

1 files changed, 42 insertions, 8 deletions

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index a1ea5f6a8d39..faf52c005e8c 100644
--- 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;
 }