Fix detection of older DS1621.

git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@5613 7894878c-1315-0410-8ee3-d5d059ff63e0

CHANGES

@@ -4,6 +4,7 @@ lm_sensors CHANGES file
 SVN-HEAD
   File lm_sensors.lsm: Delete, don't advertise a legacy branch
   File doc/developers/release_checklist: Skip mail to lsm
+  Program sensors-detect: Fix detection of older DS1621
 
 2.10.8 (20081216)
   File doc/chips/lm90: Update datasheet links (2.6 backport)

prog/detect/sensors-detect

@@ -3863,10 +3863,6 @@ sub ds1621_detect
   my $conf = i2c_smbus_read_byte_data($file, 0xAC);
   return if ($conf & 0x10);
 
-  my $counter = i2c_smbus_read_byte_data($file, 0xA8);
-  my $slope = i2c_smbus_read_byte_data($file, 0xA9);
-  return if ($slope != 0x10 || $counter > $slope);
-
   my $temp = i2c_smbus_read_word_data($file, 0xAA);
   return if $temp < 0 || ($temp & 0x0f00);
   # On the DS1631, the following two checks are too strict in theory,
@@ -3879,7 +3875,11 @@ sub ds1621_detect
 
   return if ($temp == 0 && $high == 0 && $low == 0 && $conf == 0);
 
-  return 3;
+  # Old versions of the DS1621 apparently don't have the counter and 
+  # slope registers (or they return crap) 
+  my $counter = i2c_smbus_read_byte_data($file, 0xA8);
+  my $slope = i2c_smbus_read_byte_data($file, 0xA9);
+  return ($slope == 0x10 && $counter <= $slope) ? 3 : 2;
 }
 
 # $_[0]: A reference to the file descriptor to access this chip.