pwm: Don't use memcmp() to compare state variables

Given that struct pwm_state is sparse (at least on some platforms),
variables of this type might represent the same state because all fields
are pairwise identical but still memcmp() returns a difference because
some of the unused bits are different.

To prevent surprises compare member by member instead of the whole
occupied memory.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 1581f6ab1b1f425986cb8693a961cee7fa4f42f8..253a459fe0d8df5c668e1f7956182416dcdb68c7 100644 (file)
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -472,7 +472,10 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)
            state->duty_cycle > state->period)
                return -EINVAL;
 
-       if (!memcmp(state, &pwm->state, sizeof(*state)))
+       if (state->period == pwm->state.period &&
+           state->duty_cycle == pwm->state.duty_cycle &&
+           state->polarity == pwm->state.polarity &&
+           state->enabled == pwm->state.enabled)
                return 0;
 
        if (pwm->chip->ops->apply) {