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

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Message-ID: <20260121061134.15466-1-g-praveen@ti.com>
Date: Wed, 21 Jan 2026 11:41:34 +0530
From: Gokul Praveen <g-praveen@...com>
To: <j-keerthy@...com>, <ukleinek@...nel.org>, <linux-pwm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <g-praveen@...com>, <u-kumar1@...com>, <n-francis@...com>
Subject: [PATCH v4] pwm: tiehrpwm: Enable pwmchip's parent device before setting  configuration

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@...com>
---
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