From: Kamil Debski <k.debski@samsung.com>
To: linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org
Cc: linux@roeck-us.net, Kamil Debski <k.debski@samsung.com>
Subject: [PATCH] hwmon: (pwm-fan) Fix suspend/resume behavior
Date: Mon, 03 Nov 2014 15:42:55 +0100
Message-id: <1415025775-24237-1-git-send-email-k.debski@samsung.com>
Sender: linux-kernel-owner@vger.kernel.org

The state of a PWM output is not clearly defined after resume. Some PWM
drivers do not restore the duty cycle upon resume, thus it is necessary to
manually restore the correct value.

Signed-off-by: Kamil Debski <k.debski@samsung.com>
---
 drivers/hwmon/pwm-fan.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 823c877..1991d903 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -161,10 +161,17 @@ static int pwm_fan_suspend(struct device *dev)
 static int pwm_fan_resume(struct device *dev)
 {
 	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+	unsigned long duty;
+	int ret;
 
-	if (ctx->pwm_value)
-		return pwm_enable(ctx->pwm);
-	return 0;
+	if (ctx->pwm_value == 0)
+		return 0;
+
+	duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
+	ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
+	if (ret)
+		return ret;
+	return pwm_enable(ctx->pwm);
 }
 #endif
 
-- 
1.7.9.5

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