It was necessary to decouple code handling writing to sysfs from the one
responsible for setting PWM of the fan.
Due to that, new __set_pwm() method was extracted, which is responsible for
only setting new PWM duty cycle.

Signed-off-by: Lukasz Majewski <l.majew...@samsung.com>
---
Changes for v2:
- None
Changes for v3:
- The commit headline has been reedited.
Changes for v4:
- Protect "if (ctx->pwm_value == pwm)" with ctx lock
- Initialize ret with zero
---
 drivers/hwmon/pwm-fan.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 1991d903..bd42d39 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -33,20 +33,14 @@ struct pwm_fan_ctx {
        unsigned char pwm_value;
 };
 
-static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
-                      const char *buf, size_t count)
+static int  __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
 {
-       struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
-       unsigned long pwm, duty;
-       ssize_t ret;
-
-       if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
-               return -EINVAL;
+       unsigned long duty;
+       int ret = 0;
 
        mutex_lock(&ctx->lock);
-
        if (ctx->pwm_value == pwm)
-               goto exit_set_pwm_no_change;
+               goto exit_set_pwm_err;
 
        if (pwm == 0) {
                pwm_disable(ctx->pwm);
@@ -66,13 +60,28 @@ static ssize_t set_pwm(struct device *dev, struct 
device_attribute *attr,
 
 exit_set_pwm:
        ctx->pwm_value = pwm;
-exit_set_pwm_no_change:
-       ret = count;
 exit_set_pwm_err:
        mutex_unlock(&ctx->lock);
        return ret;
 }
 
+static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
+                      const char *buf, size_t count)
+{
+       struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+       unsigned long pwm;
+       int ret;
+
+       if (kstrtoul(buf, 10, &pwm) || pwm > MAX_PWM)
+               return -EINVAL;
+
+       ret = __set_pwm(ctx, pwm);
+       if (ret)
+               return ret;
+
+       return count;
+}
+
 static ssize_t show_pwm(struct device *dev,
                        struct device_attribute *attr, char *buf)
 {
-- 
2.0.0.rc2

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