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Commit 33cdcee0 authored by Boris Brezillon's avatar Boris Brezillon Committed by Thierry Reding
Browse files

pwm: Fix pwm_apply_args() 



Commit 5ec803ed ("pwm: Add core infrastructure to allow atomic
updates"), implemented pwm_disable() as a wrapper around
pwm_apply_state(), and then, commit ef2bf499 ("pwm: Improve args
checking in pwm_apply_state()") added missing checks on the ->period
value in pwm_apply_state() to ensure we were not passing inappropriate
values to the ->config() or ->apply() methods.

The conjunction of these 2 commits led to a case where pwm_disable()
was no longer succeeding, thus preventing the polarity setting done
in pwm_apply_args().

Set a valid period in pwm_apply_args() to ensure polarity setting
won't be rejected.

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Reported-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Suggested-by: default avatarBrian Norris <briannorris@chromium.org>
Fixes: 5ec803ed ("pwm: Add core infrastructure to allow atomic updates")
Tested-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: default avatarBrian Norris <briannorris@chromium.org>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent cc51846b

include/linux/pwm.h

+10 −6
Original line number Diff line number Diff line
@@ -464,6 +464,8 @@ static inline bool pwm_can_sleep(struct pwm_device *pwm) 


static inline void pwm_apply_args(struct pwm_device *pwm)

{

	struct pwm_state state = { };



	/*

	 * PWM users calling pwm_apply_args() expect to have a fresh config

	 * where the polarity and period are set according to pwm_args info.
@@ -476,18 +478,20 @@ static inline void pwm_apply_args(struct pwm_device *pwm) 
	 * at startup (even if they are actually enabled), thus authorizing

	 * polarity setting.

	 *

	 * Instead of setting ->enabled to false, we call pwm_disable()

	 * before pwm_set_polarity() to ensure that everything is configured

	 * as expected, and the PWM is really disabled when the user request

	 * it.

	 * To fulfill this requirement, we apply a new state which disables

	 * the PWM device and set the reference period and polarity config.

	 *

	 * Note that PWM users requiring a smooth handover between the

	 * bootloader and the kernel (like critical regulators controlled by

	 * PWM devices) will have to switch to the atomic API and avoid calling

	 * pwm_apply_args().

	 */

	pwm_disable(pwm);

	pwm_set_polarity(pwm, pwm->args.polarity);



	state.enabled = false;

	state.polarity = pwm->args.polarity;

	state.period = pwm->args.period;



	pwm_apply_state(pwm, &state);

}



struct pwm_lookup {