[PATCH] hwmon: (pwm-fan) Fix suspend/resume behavior

* [PATCH] hwmon: (pwm-fan) Fix suspend/resume behavior
@ 2014-11-03 14:42 Kamil Debski
  2014-11-03 16:19 ` Guenter Roeck
  0 siblings, 1 reply; 2+ messages in thread
From: Kamil Debski @ 2014-11-03 14:42 UTC (permalink / raw)
  To: linux-kernel, lm-sensors; +Cc: linux, Kamil Debski

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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