w83627ehf: Fix the detection of fan5

Fix the detection of fan5 and preserve the bit between the
register writes, because the bit is write only.

Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/hwmon/w83627ehf.c b/drivers/hwmon/w83627ehf.c
index 833faa275ffa..2257806d0102 100644
--- a/drivers/hwmon/w83627ehf.c
+++ b/drivers/hwmon/w83627ehf.c
@@ -354,6 +354,8 @@ static void w83627ehf_write_fan_div(struct i2c_client *client, int nr)
         case 0:
                 reg = (w83627ehf_read_value(client, W83627EHF_REG_FANDIV1) & 0xcf)
                     | ((data->fan_div[0] & 0x03) << 4);
+                /* fan5 input control bit is write only, compute the value */
+                reg |= (data->has_fan & (1 << 4)) ? 1 : 0;
                 w83627ehf_write_value(client, W83627EHF_REG_FANDIV1, reg);
                 reg = (w83627ehf_read_value(client, W83627EHF_REG_VBAT) & 0xdf)
                     | ((data->fan_div[0] & 0x04) << 3);
@@ -362,6 +364,8 @@ static void w83627ehf_write_fan_div(struct i2c_client *client, int nr)
         case 1:
                 reg = (w83627ehf_read_value(client, W83627EHF_REG_FANDIV1) & 0x3f)
                     | ((data->fan_div[1] & 0x03) << 6);
+                /* fan5 input control bit is write only, compute the value */
+                reg |= (data->has_fan & (1 << 4)) ? 1 : 0;
                 w83627ehf_write_value(client, W83627EHF_REG_FANDIV1, reg);
                 reg = (w83627ehf_read_value(client, W83627EHF_REG_VBAT) & 0xbf)
                     | ((data->fan_div[1] & 0x04) << 4);
@@ -1216,13 +1220,16 @@ static int w83627ehf_detect(struct i2c_adapter *adapter)
         superio_exit();
 
         /* It looks like fan4 and fan5 pins can be alternatively used
-           as fan on/off switches */
+           as fan on/off switches, but fan5 control is write only :/
+           We assume that if the serial interface is disabled, designers
+           connected fan5 as input unless they are emitting log 1, which
+           is not the default. */
 
         data->has_fan = 0x07; /* fan1, fan2 and fan3 */
         i = w83627ehf_read_value(client, W83627EHF_REG_FANDIV1);
         if ((i & (1 << 2)) && (!fan4pin))
                 data->has_fan |= (1 << 3);
-        if ((i & (1 << 0)) && (!fan5pin))
+        if (!(i & (1 << 1)) && (!fan5pin))
                 data->has_fan |= (1 << 4);
 
         /* Register sysfs hooks */