pwm: omap-dmtimer: Drop locking

The pwm driver only provides a single PWM line, so there are no concurrent
calls of the callbacks from different consumers. A single consumer is
expected not to do concurrent calls into the pwm framework. So there is
nothing to serialize and the lock can go away.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-omap-dmtimer.c

@@ -37,7 +37,6 @@
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <clocksource/timer-ti-dm.h>
@@ -55,7 +54,6 @@
  * struct pwm_omap_dmtimer_chip - Structure representing a pwm chip
  *				  corresponding to omap dmtimer.
  * @chip:		PWM chip structure representing PWM controller
- * @mutex:		Mutex to protect pwm apply state
  * @dm_timer:		Pointer to omap dm timer.
  * @pdata:		Pointer to omap dm timer ops.
  * @dm_timer_pdev:	Pointer to omap dm timer platform device
@@ -63,7 +61,6 @@
 struct pwm_omap_dmtimer_chip {
 	struct pwm_chip chip;
 	/* Mutex to protect pwm apply state */
-	struct mutex mutex;
 	struct omap_dm_timer *dm_timer;
 	const struct omap_dm_timer_ops *pdata;
 	struct platform_device *dm_timer_pdev;
@@ -277,13 +274,11 @@ static int pwm_omap_dmtimer_apply(struct pwm_chip *chip,
 				  const struct pwm_state *state)
 {
 	struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
-	int ret = 0;
-
-	mutex_lock(&omap->mutex);
+	int ret;
 
 	if (pwm_omap_dmtimer_is_enabled(omap) && !state->enabled) {
 		omap->pdata->stop(omap->dm_timer);
-		goto unlock_mutex;
+		return 0;
 	}
 
 	if (pwm_omap_dmtimer_polarity(omap) != state->polarity)
@@ -292,7 +287,7 @@ static int pwm_omap_dmtimer_apply(struct pwm_chip *chip,
 	ret = pwm_omap_dmtimer_config(chip, pwm, state->duty_cycle,
 				      state->period);
 	if (ret)
-		goto unlock_mutex;
+		return ret;
 
 	if (!pwm_omap_dmtimer_is_enabled(omap) && state->enabled) {
 		omap->pdata->set_pwm(omap->dm_timer,
@@ -303,10 +298,7 @@ static int pwm_omap_dmtimer_apply(struct pwm_chip *chip,
 		pwm_omap_dmtimer_start(omap);
 	}
 
-unlock_mutex:
-	mutex_unlock(&omap->mutex);
-
-	return ret;
+	return 0;
 }
 
 static const struct pwm_ops pwm_omap_dmtimer_ops = {
@@ -404,8 +396,6 @@ static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
 	omap->chip.ops = &pwm_omap_dmtimer_ops;
 	omap->chip.npwm = 1;
 
-	mutex_init(&omap->mutex);
-
 	ret = pwmchip_add(&omap->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to register PWM\n");
@@ -452,8 +442,6 @@ static void pwm_omap_dmtimer_remove(struct platform_device *pdev)
 	omap->pdata->free(omap->dm_timer);
 
 	put_device(&omap->dm_timer_pdev->dev);
-
-	mutex_destroy(&omap->mutex);
 }
 
 static const struct of_device_id pwm_omap_dmtimer_of_match[] = {