linux-kernel - [PATCH v6 3/7] pwm: pca9685: Improve runtime PM behavior

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Date:   Mon, 29 Mar 2021 14:57:03 +0200
From:   Clemens Gruber <clemens.gruber@...ruber.com>
To:     linux-pwm@...r.kernel.org
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Sven Van Asbroeck <TheSven73@...il.com>,
        u.kleine-koenig@...gutronix.de, linux-kernel@...r.kernel.org,
        Clemens Gruber <clemens.gruber@...ruber.com>
Subject: [PATCH v6 3/7] pwm: pca9685: Improve runtime PM behavior

The chip does not come out of POR in active state but in sleep state.
To be sure (in case the bootloader woke it up) we force it to sleep in
probe.

On kernels without CONFIG_PM, we wake the chip in .probe and put it to
sleep in .remove.

Signed-off-by: Clemens Gruber <clemens.gruber@...ruber.com>
---
 drivers/pwm/pwm-pca9685.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index fb026a25fb61..4d6684b90819 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -469,14 +469,19 @@ static int pca9685_pwm_probe(struct i2c_client *client,
 		return ret;
 	}
 
-	/* The chip comes out of power-up in the active state */
-	pm_runtime_set_active(&client->dev);
 	/*
-	 * Enable will put the chip into suspend, which is what we
-	 * want as all outputs are disabled at this point
+	 * The chip comes out of power-up in the sleep state,
+	 * but force it to sleep in case it was woken up before
 	 */
+	pca9685_set_sleep_mode(pca, true);
+	pm_runtime_set_suspended(&client->dev);
 	pm_runtime_enable(&client->dev);
 
+	if (!IS_ENABLED(CONFIG_PM)) {
+		/* Wake the chip up on non-PM environments */
+		pca9685_set_sleep_mode(pca, false);
+	}
+
 	return 0;
 }
 
@@ -488,7 +493,14 @@ static int pca9685_pwm_remove(struct i2c_client *client)
 	ret = pwmchip_remove(&pca->chip);
 	if (ret)
 		return ret;
+
 	pm_runtime_disable(&client->dev);
+
+	if (!IS_ENABLED(CONFIG_PM)) {
+		/* Put chip in sleep state on non-PM environments */
+		pca9685_set_sleep_mode(pca, true);
+	}
+
 	return 0;
 }
 
-- 
2.31.1