in core.c [129:138]
static int mux_control_set(struct mux_control *mux, int state)
{
int ret = mux->chip->ops->set(mux, state);
mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
if (ret >= 0)
mux->last_change = ktime_get();
return ret;
}