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Subject[PATCH v2 3/3] leds: leds-pwm: Defer led_pwm_set() if PWM can sleep
Date
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>
---
drivers/leds/leds-pwm.c | 50 +++++++++++++++++++++++++++++++++++++++-------
1 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index a1ea5f6..70effa7 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;
+ unsigned can_sleep:1;
};

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_cansleep(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_cansleep(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;
}
--
1.7.5.4


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