[PATCH v4] pwm: tiehrpwm: Enable pwmchip's parent device before setting configuration

[Gokul Praveen]

The period and duty cycle configurations on J7200 and J784S4 SoCs
does not get reflected after setting them using sysfs nodes.
This is because at the end of ehrpwm_pwm_config function,
the put_sync function is called which resets the hardware.

Hold the PWM controller out of low-power mode during .apply() to
make sure it accepts the writes to its registers.

This renders the calls to pm_runtime_get_sync() and
pm_runtime_put_sync() in ehrpwm_pwm_config() into no-ops, so
these can be dropped.

Fixes: 5f027d9b83db("pwm: tiehrpwm: Implement .apply() callback")
Signed-off-by: Gokul Praveen <g-praveen@xxxxxx>
---
v4 <==> v3
===========
* Modified subject line and commit description for better clarity.

v3 <==> v2
==========
* Simplified the logic by adding guard function for runtime power
  management.

v2 <==> v1
==========
* Removed space between Fixes and Signed-off tag

 drivers/pwm/pwm-tiehrpwm.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c
index 7a86cb090f76..2533c95b0ba9 100644
--- a/drivers/pwm/pwm-tiehrpwm.c
+++ b/drivers/pwm/pwm-tiehrpwm.c
@@ -237,8 +237,6 @@ static int ehrpwm_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (period_cycles < 1)
 		period_cycles = 1;
 
-	pm_runtime_get_sync(pwmchip_parent(chip));
-
 	/* Update clock prescaler values */
 	ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CLKDIV_MASK, tb_divval);
 
@@ -290,8 +288,6 @@ static int ehrpwm_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (!(duty_cycles > period_cycles))
 		ehrpwm_write(pc->mmio_base, cmp_reg, duty_cycles);
 
-	pm_runtime_put_sync(pwmchip_parent(chip));
-
 	return 0;
 }
 
@@ -378,6 +374,8 @@ static int ehrpwm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	int err;
 	bool enabled = pwm->state.enabled;
 
+	guard(pm_runtime_active)(pwmchip_parent(chip));
+
 	if (state->polarity != pwm->state.polarity) {
 		if (enabled) {
 			ehrpwm_pwm_disable(chip, pwm);
-- 
2.34.1