linux-kernel - [PATCH v9 3/8] pwm: pca9685: Improve runtime PM behavior

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 15 Apr 2021 14:14:50 +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>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Clemens Gruber <clemens.gruber@...ruber.com>
Subject: [PATCH v9 3/8] 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.

If runtime PM is disabled, we instead wake the chip in .probe and put it
to sleep in .remove.

Signed-off-by: Clemens Gruber <clemens.gruber@...ruber.com>
---
Changes since v8:
- Rebased

Changes since v7:
- Handle sysfs power control as well and not just CONFIG_PM

Changes since v6:
- Improved !CONFIG_PM handling (wake it up without putting it to sleep
  first)

 drivers/pwm/pwm-pca9685.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index aa48c45bd294..1b013d03f5d8 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -462,14 +462,20 @@ 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
-	 */
 	pm_runtime_enable(&client->dev);
 
+	if (pm_runtime_enabled(&client->dev)) {
+		/*
+		 * Although the chip comes out of power-up in the sleep state,
+		 * we force it to sleep in case it was woken up before
+		 */
+		pca9685_set_sleep_mode(pca, true);
+		pm_runtime_set_suspended(&client->dev);
+	} else {
+		/* Wake the chip up if runtime PM is disabled */
+		pca9685_set_sleep_mode(pca, false);
+	}
+
 	return 0;
 }
 
@@ -481,7 +487,14 @@ static int pca9685_pwm_remove(struct i2c_client *client)
 	ret = pwmchip_remove(&pca->chip);
 	if (ret)
 		return ret;
+
+	if (!pm_runtime_enabled(&client->dev)) {
+		/* Put chip in sleep state if runtime PM is disabled */
+		pca9685_set_sleep_mode(pca, true);
+	}
+
 	pm_runtime_disable(&client->dev);
+
 	return 0;
 }
 
-- 
2.31.1