pwm: Fix pwm_apply_args() (33cdcee0) · Commits · 戴 / test

Commit ("pwm: Add core infrastructure to allow atomic updates"), implemented pwm_disable() as a wrapper around pwm_apply_state(), and then, commit ("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:

Boris Brezillon <boris.brezillon@free-electrons.com> Reported-by:

Geert Uytterhoeven <geert@linux-m68k.org> Suggested-by:

Brian Norris <briannorris@chromium.org> Fixes: ("pwm: Add core infrastructure to allow atomic updates") Tested-by:

Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by:

Brian Norris <briannorris@chromium.org> Signed-off-by:

Thierry Reding <thierry.reding@gmail.com>

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 {

Admin message