Merge tag 'pwm/for-6.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm fixes from Thierry Reding:
 "These are some fixes to make sure the PWM state structure is always
  initialized to a known state.

  Prior to this it could happen in some situations that random data from
  the stack would leak into the data structure and cause subtle bugs"

* tag 'pwm/for-6.3-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
  pwm: Zero-initialize the pwm_state passed to driver's .get_state()
  pwm: meson: Explicitly set .polarity in .get_state()
  pwm: sprd: Explicitly set .polarity in .get_state()
  pwm: iqs620a: Explicitly set .polarity in .get_state()
  pwm: cros-ec: Explicitly set .polarity in .get_state()
  pwm: hibvt: Explicitly set .polarity in .get_state()

Author: torvalds

drivers/pwm/core.c

@@ -115,7 +115,14 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	}
 
 	if (pwm->chip->ops->get_state) {
-		struct pwm_state state;
+		/*
+		 * Zero-initialize state because most drivers are unaware of
+		 * .usage_power. The other members of state are supposed to be
+		 * set by lowlevel drivers. We still initialize the whole
+		 * structure for simplicity even though this might paper over
+		 * faulty implementations of .get_state().
+		 */
+		struct pwm_state state = { 0, };
 
 		err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
 		trace_pwm_get(pwm, &state, err);
@@ -448,7 +455,7 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 {
 	struct pwm_state *last = &pwm->last;
 	struct pwm_chip *chip = pwm->chip;
-	struct pwm_state s1, s2;
+	struct pwm_state s1 = { 0 }, s2 = { 0 };
 	int err;
 
 	if (!IS_ENABLED(CONFIG_PWM_DEBUG))
@@ -530,6 +537,7 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 		return;
 	}
 
+	*last = (struct pwm_state){ 0 };
 	err = chip->ops->get_state(chip, pwm, last);
 	trace_pwm_get(pwm, last, err);
 	if (err)

drivers/pwm/pwm-cros-ec.c

@@ -198,6 +198,7 @@ static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	state->enabled = (ret > 0);
 	state->period = EC_PWM_MAX_DUTY;
+	state->polarity = PWM_POLARITY_NORMAL;
 
 	/*
 	 * Note that "disabled" and "duty cycle == 0" are treated the same. If

drivers/pwm/pwm-hibvt.c

@@ -146,6 +146,7 @@ static int hibvt_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	value = readl(base + PWM_CTRL_ADDR(pwm->hwpwm));
 	state->enabled = (PWM_ENABLE_MASK & value);
+	state->polarity = (PWM_POLARITY_MASK & value) ? PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
 
 	return 0;
 }

drivers/pwm/pwm-iqs620a.c

@@ -126,6 +126,7 @@ static int iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	mutex_unlock(&iqs620_pwm->lock);
 
 	state->period = IQS620_PWM_PERIOD_NS;
+	state->polarity = PWM_POLARITY_NORMAL;
 
 	return 0;
 }

drivers/pwm/pwm-meson.c

@@ -162,6 +162,12 @@ static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
 	duty = state->duty_cycle;
 	period = state->period;
 
+	/*
+	 * Note this is wrong. The result is an output wave that isn't really
+	 * inverted and so is wrongly identified by .get_state as normal.
+	 * Fixing this needs some care however as some machines might rely on
+	 * this.
+	 */
 	if (state->polarity == PWM_POLARITY_INVERSED)
 		duty = period - duty;
 
@@ -358,6 +364,8 @@ static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 		state->duty_cycle = 0;
 	}
 
+	state->polarity = PWM_POLARITY_NORMAL;
+
 	return 0;
 }
 

drivers/pwm/pwm-sprd.c

@@ -109,6 +109,7 @@ static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	duty = val & SPRD_PWM_DUTY_MSK;
 	tmp = (prescale + 1) * NSEC_PER_SEC * duty;
 	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
+	state->polarity = PWM_POLARITY_NORMAL;
 
 	/* Disable PWM clocks if the PWM channel is not in enable state. */
 	if (!state->enabled)