From: Maarten ter Huurne <maarten@xxxxxxxxxxxxxx>
On the JZ4750 and later SoCs, channel 1 and 2 operate in a different
way (TCU2 mode) as the other channels. If a TCU2 mode counter is
stopped before its PWM functionality is disabled, the output is not
guaranteed to return to the initial level.
Signed-off-by: Maarten ter Huurne <maarten@xxxxxxxxxxxxxx>
---
drivers/pwm/pwm-jz4740.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index a75ff3622450..2e41ba213f39 100644
--- a/drivers/pwm/pwm-jz4740.c
+++ b/drivers/pwm/pwm-jz4740.c
@@ -71,9 +71,15 @@ static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
+ /* Disable PWM output.
+ * In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
+ * counter is stopped, while in TCU1 mode the order does not matter.
+ */
ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
- jz4740_timer_disable(pwm->hwpwm);
jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
+
+ /* Stop counter */
+ jz4740_timer_disable(pwm->hwpwm);
}
static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
--
2.11.0
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
