Merge pull request #91 from desowin/pwm-readback-fan2go-workaround

[RFC] Update cached pwm values on pwm store

nct6687.c

@@ -789,6 +789,8 @@ static ssize_t store_pwm(struct device *dev, struct device_attribute *attr, cons
 	struct nct6687_data *data = dev_get_drvdata(dev);
 	int index = sattr->index;
 	unsigned long val;
+	int retry;
+	u16 readback;
 	u16 mode;
 	u8 bitMask;
 
@@ -809,7 +811,16 @@ static ssize_t store_pwm(struct device *dev, struct device_attribute *attr, cons
 	msleep(50);
 	nct6687_write(data, NCT6687_REG_PWM_WRITE(index), val);
 	nct6687_write(data, NCT6687_REG_FAN_PWM_COMMAND(index), NCT6687_FAN_CFG_DONE);
-	msleep(50);
+
+	for (retry = 0; retry < 20; retry++) {
+		msleep(50);
+
+		readback = nct6687_read(data, NCT6687_REG_PWM(index));
+		if (readback == val)
+			break;
+	}
+	data->pwm[index] = readback;
+	data->pwm_enable[index] = nct6687_get_pwm_enable(data, index);
 
 	mutex_unlock(&data->update_lock);