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Commit b526a314 authored by Hans de Goede's avatar Hans de Goede Committed by Thierry Reding
Browse files

pwm: Try to load modules during pwm_get() 



Add a module name string to the pwm_lookup struct and if specified try
to load the module using request_module() if pwmchip_find_by_name() is
unable to find the PWM chip.

This is a last resort to work around drivers that can't - and can't be
made to - deal with deferred probe.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
[thierry.reding@gmail.com: rename new macro, reword commit message]
[thierry.reding@gmail.com: add comment explaining use-case]
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 69efb343

drivers/pwm/core.c

+14 −0
Original line number Diff line number Diff line
@@ -765,6 +765,7 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) 
	unsigned int best = 0;

	struct pwm_lookup *p, *chosen = NULL;

	unsigned int match;

	int err;



	/* look up via DT first */

	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
@@ -825,6 +826,19 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) 
		return ERR_PTR(-ENODEV);



	chip = pwmchip_find_by_name(chosen->provider);



	/*

	 * If the lookup entry specifies a module, load the module and retry

	 * the PWM chip lookup. This can be used to work around driver load

	 * ordering issues if driver's can't be made to properly support the

	 * deferred probe mechanism.

	 */

	if (!chip && chosen->module) {

		err = request_module(chosen->module);

		if (err == 0)

			chip = pwmchip_find_by_name(chosen->provider);

	}



	if (!chip)

		return ERR_PTR(-EPROBE_DEFER);

include/linux/pwm.h

+15 −8
Original line number Diff line number Diff line
@@ -603,18 +603,25 @@ struct pwm_lookup { 
	const char *con_id;

	unsigned int period;

	enum pwm_polarity polarity;

	const char *module; /* optional, may be NULL */

};



#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \

#define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id,	\

			       _period, _polarity, _module)		\

	{								\

		.provider = _provider,					\

		.index = _index,					\

		.dev_id = _dev_id,					\

		.con_id = _con_id,					\

		.period = _period,					\

		.polarity = _polarity			\

		.polarity = _polarity,					\

		.module = _module,					\

	}



#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \

	PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \

			       _polarity, NULL)



#if IS_ENABLED(CONFIG_PWM)

void pwm_add_table(struct pwm_lookup *table, size_t num);

void pwm_remove_table(struct pwm_lookup *table, size_t num);