After commit a020f22a4ff5 ("pwm: jz4740: Make PWM start with the active part"),
the trick to set duty > period to properly shut down TCU2 channels did
not work anymore, because of the polarity inversion.
Address this issue by restoring the proper polarity before disabling the
channels.
Fixes: a020f22a4ff5 ("pwm: jz4740: Make PWM start with the active part")
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/pwm/pwm-jz4740.c | 62 ++++++++++++++++++++++++++--------------
1 file changed, 40 insertions(+), 22 deletions(-)
diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index 228eb104bf1e..65462a0052af 100644
--- a/drivers/pwm/pwm-jz4740.c
+++ b/drivers/pwm/pwm-jz4740.c
@@ -97,6 +97,19 @@ static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
return 0;
}
+static void jz4740_pwm_set_polarity(struct jz4740_pwm_chip *jz,
+ unsigned int hwpwm,
+ enum pwm_polarity polarity)
+{
+ unsigned int value = 0;
+
+ if (polarity == PWM_POLARITY_INVERSED)
+ value = TCU_TCSR_PWM_INITL_HIGH;
+
+ regmap_update_bits(jz->map, TCU_REG_TCSRc(hwpwm),
+ TCU_TCSR_PWM_INITL_HIGH, value);
+}
+
static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct jz4740_pwm_chip *jz = to_jz4740(chip);
@@ -130,6 +143,7 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
struct clk *clk = pwm_get_chip_data(pwm);
unsigned long period, duty;
+ enum pwm_polarity polarity;
long rate;
int err;
@@ -169,6 +183,9 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
if (duty >= period)
duty = period - 1;
+ /* Restore regular polarity before disabling the channel. */
+ jz4740_pwm_set_polarity(jz4740, pwm->hwpwm, state->polarity);
+
jz4740_pwm_disable(chip, pwm);
err = clk_set_rate(clk, rate);
@@ -190,29 +207,30 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD);
- /*
- * Set polarity.
- *
- * The PWM starts in inactive state until the internal timer reaches the
- * duty value, then becomes active until the timer reaches the period
- * value. In theory, we should then use (period - duty) as the real duty
- * value, as a high duty value would otherwise result in the PWM pin
- * being inactive most of the time.
- *
- * Here, we don't do that, and instead invert the polarity of the PWM
- * when it is active. This trick makes the PWM start with its active
- * state instead of its inactive state.
- */
- if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
- regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
- TCU_TCSR_PWM_INITL_HIGH, 0);
- else
- regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
- TCU_TCSR_PWM_INITL_HIGH,
- TCU_TCSR_PWM_INITL_HIGH);
-
- if (state->enabled)
+ if (state->enabled) {
+ /*
+ * Set polarity.
+ *
+ * The PWM starts in inactive state until the internal timer
+ * reaches the duty value, then becomes active until the timer
+ * reaches the period value. In theory, we should then use
+ * (period - duty) as the real duty value, as a high duty value
+ * would otherwise result in the PWM pin being inactive most of
+ * the time.
+ *
+ * Here, we don't do that, and instead invert the polarity of
+ * the PWM when it is active. This trick makes the PWM start
+ * with its active state instead of its inactive state.
+ */
+ if (state->polarity == PWM_POLARITY_NORMAL)
+ polarity = PWM_POLARITY_INVERSED;
+ else
+ polarity = PWM_POLARITY_NORMAL;
+
+ jz4740_pwm_set_polarity(jz4740, pwm->hwpwm, polarity);
+
jz4740_pwm_enable(chip, pwm);
+ }
return 0;
}
--
2.35.1
