Commit d1cd2142 authored by Jonathan Richardson's avatar Jonathan Richardson Committed by Thierry Reding
Browse files

pwm: Set enable state properly on failed call to enable 



The pwm_enable() function didn't clear the enabled bit if a call to the
driver's ->enable() callback returned an error. The result was that the
state of the PWM core was wrong. Clearing the bit when enable returns
an error ensures the state is properly set.

Tested-by: default avatarJonathan Richardson <jonathar@broadcom.com>
Reviewed-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: default avatarJonathan Richardson <jonathar@broadcom.com>
[thierry.reding@gmail.com: add missing kerneldoc for the lock]
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent f080be27

drivers/pwm/core.c

+26 −7
Original line number Diff line number Diff line
@@ -269,6 +269,7 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, 
		pwm->pwm = chip->base + i;

		pwm->hwpwm = i;

		pwm->polarity = polarity;

		mutex_init(&pwm->lock);



		radix_tree_insert(&pwm_tree, pwm->pwm, pwm);

	}
@@ -473,16 +474,22 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) 
	if (!pwm->chip->ops->set_polarity)

		return -ENOSYS;



	if (pwm_is_enabled(pwm))

		return -EBUSY;

	mutex_lock(&pwm->lock);



	if (pwm_is_enabled(pwm)) {

		err = -EBUSY;

		goto unlock;

	}



	err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);

	if (err)

		return err;

		goto unlock;



	pwm->polarity = polarity;



	return 0;

unlock:

	mutex_unlock(&pwm->lock);

	return err;

}

EXPORT_SYMBOL_GPL(pwm_set_polarity);
@@ -494,10 +501,22 @@ EXPORT_SYMBOL_GPL(pwm_set_polarity); 
 */

int pwm_enable(struct pwm_device *pwm)

{

	if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))

		return pwm->chip->ops->enable(pwm->chip, pwm);

	int err = 0;



	if (!pwm)

		return -EINVAL;



	mutex_lock(&pwm->lock);



	if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {

		err = pwm->chip->ops->enable(pwm->chip, pwm);

		if (err)

			clear_bit(PWMF_ENABLED, &pwm->flags);

	}



	return pwm ? 0 : -EINVAL;

	mutex_unlock(&pwm->lock);



	return err;

}

EXPORT_SYMBOL_GPL(pwm_enable);

include/linux/pwm.h

+3 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#define __LINUX_PWM_H



#include <linux/err.h>

#include <linux/mutex.h>

#include <linux/of.h>



struct pwm_device;
@@ -87,6 +88,7 @@ enum { 
 * @pwm: global index of the PWM device

 * @chip: PWM chip providing this PWM device

 * @chip_data: chip-private data associated with the PWM device

 * @lock: used to serialize accesses to the PWM device where necessary

 * @period: period of the PWM signal (in nanoseconds)

 * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)

 * @polarity: polarity of the PWM signal
@@ -98,6 +100,7 @@ struct pwm_device { 
	unsigned int pwm;

	struct pwm_chip *chip;

	void *chip_data;

	struct mutex lock;



	unsigned int period;

	unsigned int duty_cycle;

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