Setting w83627hf fan_div preserves fan_min

@@ -659,34 +659,37 @@
 		       (long) DIV_FROM_REG(data->fan_div[nr - 1]));
 }
 
+/* Note: we save and restore the fan minimum here, because its value is
+   determined in part by the fan divisor.  This follows the principle of
+   least suprise; the user doesn't expect the fan minimum to change just
+   because the divisor changed. */
 static ssize_t
 store_fan_div_reg(struct device *dev, const char *buf, size_t count, int nr)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct w83627hf_data *data = i2c_get_clientdata(client);
-	u32 val, old, old2, old3 = 0;
+	unsigned long min;
+	u8 reg;
 
-	val = simple_strtoul(buf, NULL, 10);
-	old = w83627hf_read_value(client, W83781D_REG_VID_FANDIV);
-	old3 = w83627hf_read_value(client, W83781D_REG_VBAT);
-	data->fan_div[nr - 1] = DIV_TO_REG(val);
-
-	if (nr >= 3 && data->type != w83697hf) {
-		old2 = w83627hf_read_value(client, W83781D_REG_PIN);
-		old2 = (old2 & 0x3f) | ((data->fan_div[2] & 0x03) << 6);
-		w83627hf_write_value(client, W83781D_REG_PIN, old2);
-		old3 = (old3 & 0x7f) | ((data->fan_div[2] & 0x04) << 5);
-	}
-	if (nr >= 2) {
-		old = (old & 0x3f) | ((data->fan_div[1] & 0x03) << 6);
-		old3 = (old3 & 0xbf) | ((data->fan_div[1] & 0x04) << 4);
-	}
-	if (nr >= 1) {
-		old = (old & 0xcf) | ((data->fan_div[0] & 0x03) << 4);
-		w83627hf_write_value(client, W83781D_REG_VID_FANDIV, old);
-		old3 = (old3 & 0xdf) | ((data->fan_div[0] & 0x04) << 3);
-		w83627hf_write_value(client, W83781D_REG_VBAT, old3);
-	}
+	/* Save fan_min */
+	min = FAN_FROM_REG(data->fan_min[nr],
+			   DIV_FROM_REG(data->fan_div[nr]));
+
+	data->fan_div[nr] = DIV_TO_REG(simple_strtoul(buf, NULL, 10));
+
+	reg = (w83627hf_read_value(client, nr=2 ? W83781D_REG_PIN : W83781D_REG_VID_FANDIV)
+	       & (nr=0 ? 0xcf : 0x3f))
+	    | ((data->fan_div[nr] & 0x03) << (nr=0 ? 4 : 6));
+	w83627hf_write_value(client, nr=2 ? W83781D_REG_PIN : W83781D_REG_VID_FANDIV, reg);
+
+	reg = (w83627hf_read_value(client, W83781D_REG_VBAT)
+	       & ~(1 << (5 + nr)))
+	    | ((data->fan_div[nr] & 0x04) << (3 + nr));
+	w83627hf_write_value(client, W83781D_REG_VBAT, reg);
+
+	/* Restore fan_min */
+	data->fan_min[nr] = FAN_TO_REG(min, DIV_FROM_REG(data->fan_div[nr]));
+	w83627hf_write_value(client, W83781D_REG_FAN_MIN(nr+1), data->fan_min[nr]);
 
 	return count;
 }

@@ -700,7 +703,7 @@
 store_regs_fan_div_##offset (struct device *dev, \
 			    const char *buf, size_t count) \
 { \
-	return store_fan_div_reg(dev, buf, count, offset); \
+	return store_fan_div_reg(dev, buf, count, offset - 1); \
 } \
 static DEVICE_ATTR(fan##offset##_div, S_IRUGO | S_IWUSR, \
 		  show_regs_fan_div_##offset, store_regs_fan_div_##offset)

@@ -981,6 +984,11 @@
 
 	/* Initialize the chip */
 	w83627hf_init_client(new_client);
+
+	/* A few vars need to be filled upon startup */
+	data->fan_min[0] = w83627hf_read_value(new_client, W83781D_REG_FAN_MIN(1));
+	data->fan_min[1] = w83627hf_read_value(new_client, W83781D_REG_FAN_MIN(2));
+	data->fan_min[2] = w83627hf_read_value(new_client, W83781D_REG_FAN_MIN(3));
 
 	/* Register sysfs hooks */
 	device_create_file_in(new_client, 0);