diff --git a/CHANGES b/CHANGES
index b8940e87..44f7fc34 100644
--- a/CHANGES
+++ b/CHANGES
@@ -19,6 +19,7 @@ SVN-HEAD
                           Don't probe I2C addresses 0x40-0x47
                           Fix the parsing of I2C addresses not to scan
                           Detect and skip 1-register-only I2C devices
+                          Avoid SMBus word transactions where possible
 
 2.10.6 "Welcome Home Lina" (20080306)
   Library: Fix fschrc and fschmd support
diff --git a/prog/detect/sensors-detect b/prog/detect/sensors-detect
index 4b032f14..c2559579 100755
--- a/prog/detect/sensors-detect
+++ b/prog/detect/sensors-detect
@@ -2724,6 +2724,10 @@ sub i2c_smbus_read_byte_data
 # $_[0]: Reference to an opened filehandle
 # $_[1]: Command byte (usually register number)
 # Returns: -1 on failure, the read word on success.
+# Use this function with care, some devices don't like word reads,
+# so you should do as much of the detection as possible using byte reads,
+# and only start using word reads when there is a good chance that
+# the detection will succeed.
 # Note: some devices use the wrong endiannes; use swap_bytes to correct for 
 # this.
 sub i2c_smbus_read_word_data
@@ -3587,46 +3591,42 @@ sub lm78_alias_detect
 # The DS75 is a bit different, it doesn't cycle over 8-byte boundaries, and
 # all register addresses from 0x04 to 0x0f behave like 0x04-0x07 do for
 # the LM75.
+# Not all devices enjoy SMBus read word transactions, so we use read byte
+# transactions even for the 16-bit registers. The low bits aren't very
+# useful for detection anyway.
 sub lm75_detect
 {
   my $i;
   my ($chip, $file, $addr) = @_;
-  my $cur = i2c_smbus_read_word_data($file,0x00);
+  my $cur = i2c_smbus_read_byte_data($file, 0x00);
   my $conf = i2c_smbus_read_byte_data($file,0x01);
 
-  my $hyst = i2c_smbus_read_word_data($file,0x02);
+  my $hyst = i2c_smbus_read_byte_data($file, 0x02);
   my $maxreg = $chip == 1 ? 0x0f : 0x07;
   for $i (0x04 .. $maxreg) {
-    return if i2c_smbus_read_word_data($file, $i) != $hyst;
+    return if i2c_smbus_read_byte_data($file, $i) != $hyst;
   }
 
-  my $os = i2c_smbus_read_word_data($file,0x03);
+  my $os = i2c_smbus_read_byte_data($file, 0x03);
   for $i (0x04 .. $maxreg) {
-    return if i2c_smbus_read_word_data($file, $i) != $os;
+    return if i2c_smbus_read_byte_data($file, $i) != $os;
   }
 
   if ($chip == 0) {
     for ($i = 8; $i <= 248; $i += 40) {
       return if i2c_smbus_read_byte_data($file, $i + 0x01) != $conf
-             or i2c_smbus_read_word_data($file, $i + 0x02) != $hyst
-             or i2c_smbus_read_word_data($file, $i + 0x03) != $os;
+             or i2c_smbus_read_byte_data($file, $i + 0x02) != $hyst
+             or i2c_smbus_read_byte_data($file, $i + 0x03) != $os;
     }
   }
 
   # All registers hold the same value, obviously a misdetection
-  return if $conf == ($cur & 0xff) and $cur == $hyst
-    and $cur == $os;
+  return if $conf == $cur and $cur == $hyst and $cur == $os;
 
-  $cur = swap_bytes($cur);
-  $hyst = swap_bytes($hyst);
-  $os = swap_bytes($os);
   # Unused bits
   return if $chip == 0 and ($conf & 0xe0);
   return if $chip == 1 and ($conf & 0x80);
 
-  $cur = $cur >> 8;
-  $hyst = $hyst >> 8;
-  $os = $os >> 8;
   # Most probable value ranges
   return 6 if $cur <= 100 and ($hyst >= 10 && $hyst <= 125)
     and ($os >= 20 && $os <= 127) and $hyst < $os;
@@ -3645,54 +3645,65 @@ sub lm75_detect
 #   0x03: Overtemperature Shutdown
 #   0x04: Low limit
 #   0x05: High limit
-#   0x04-0x07: No registers
+#   0x06-0x07: No registers
 # The first detection step is based on the fact that the LM77 has only
 # six registers, and cycles addresses over 8-byte boundaries. We use the
 # 0x06-0x07 addresses (unused) to improve the reliability. These are not
 # real registers and will always return the last returned value. This isn't
 # documented.
 # Note that register 0x00 may change, so we can't use the modulo trick on it.
+# Not all devices enjoy SMBus read word transactions, so we use read byte
+# transactions even for the 16-bit registers at first. We only use read word
+# transactions in the end when we are already almost certain that we have an
+# LM77 chip.
 sub lm77_detect
 {
   my $i;
   my ($file,$addr) = @_;
-  my $cur = i2c_smbus_read_word_data($file,0x00);
+  my $cur = i2c_smbus_read_byte_data($file, 0x00);
   my $conf = i2c_smbus_read_byte_data($file,0x01);
-  my $hyst = i2c_smbus_read_word_data($file,0x02);
-  my $os = i2c_smbus_read_word_data($file,0x03);
+  my $hyst = i2c_smbus_read_byte_data($file, 0x02);
+  my $os = i2c_smbus_read_byte_data($file, 0x03);
 
-  my $low = i2c_smbus_read_word_data($file,0x04);
-  return if i2c_smbus_read_word_data($file,0x06) != $low;
-  return if i2c_smbus_read_word_data($file,0x07) != $low;
+  my $low = i2c_smbus_read_byte_data($file, 0x04);
+  return if i2c_smbus_read_byte_data($file, 0x06) != $low;
+  return if i2c_smbus_read_byte_data($file, 0x07) != $low;
 
-  my $high = i2c_smbus_read_word_data($file,0x05);
-  return if i2c_smbus_read_word_data($file,0x06) != $high;
-  return if i2c_smbus_read_word_data($file,0x07) != $high;
+  my $high = i2c_smbus_read_byte_data($file, 0x05);
+  return if i2c_smbus_read_byte_data($file, 0x06) != $high;
+  return if i2c_smbus_read_byte_data($file, 0x07) != $high;
 
   for ($i = 8; $i <= 248; $i += 40) {
     return if i2c_smbus_read_byte_data($file, $i + 0x01) != $conf;
-    return if i2c_smbus_read_word_data($file, $i + 0x02) != $hyst;
-    return if i2c_smbus_read_word_data($file, $i + 0x03) != $os;
-    return if i2c_smbus_read_word_data($file, $i + 0x04) != $low;
-    return if i2c_smbus_read_word_data($file, $i + 0x05) != $high;
+    return if i2c_smbus_read_byte_data($file, $i + 0x02) != $hyst;
+    return if i2c_smbus_read_byte_data($file, $i + 0x03) != $os;
+    return if i2c_smbus_read_byte_data($file, $i + 0x04) != $low;
+    return if i2c_smbus_read_byte_data($file, $i + 0x05) != $high;
   }
 
   # All registers hold the same value, obviously a misdetection
-  return if $conf == ($cur & 0xff) and $cur == $hyst
+  return if $conf == $cur and $cur == $hyst
     and $cur == $os and $cur == $low and $cur == $high;
 
-  $cur = swap_bytes($cur);
-  $os = swap_bytes($os);
-  $hyst = swap_bytes($hyst);
-  $low = swap_bytes($low);
-  $high = swap_bytes($high);
   # Unused bits
   return if ($conf & 0xe0)
-    or (($cur >> 12) != 0 && ($cur >> 12) != 0xf)
-    or (($hyst >> 12) != 0 && ($hyst >> 12) != 0xf)
-    or (($os >> 12) != 0 && ($os >> 12) != 0xf)
-    or (($low >> 12) != 0 && ($low >> 12) != 0xf)
-    or (($high >> 12) != 0 && ($high >> 12) != 0xf);
+    or (($cur >> 4) != 0 && ($cur >> 4) != 0xf)
+    or (($hyst >> 4) != 0 && ($hyst >> 4) != 0xf)
+    or (($os >> 4) != 0 && ($os >> 4) != 0xf)
+    or (($low >> 4) != 0 && ($low >> 4) != 0xf)
+    or (($high >> 4) != 0 && ($high >> 4) != 0xf);
+
+  # Make sure the chip supports SMBus read word transactions
+  $cur = i2c_smbus_read_word_data($file, 0x00);
+  return if $cur < 0;
+  $hyst = i2c_smbus_read_word_data($file, 0x02);
+  return if $hyst < 0;
+  $os = i2c_smbus_read_word_data($file, 0x03);
+  return if $os < 0;
+  $low = i2c_smbus_read_word_data($file, 0x04);
+  return if $low < 0;
+  $high = i2c_smbus_read_word_data($file, 0x05);
+  return if $high < 0;
 
   $cur /= 16;
   $hyst /= 16;
@@ -3720,33 +3731,48 @@ sub lm77_detect
 # One detection step is based on the fact that the LM92 and clones have a
 # limited number of registers, which cycle modulo 16 address values.
 # Note that register 0x00 may change, so we can't use the modulo trick on it.
+# Not all devices enjoy SMBus read word transactions, so we use read byte
+# transactions even for the 16-bit registers at first. We only use read
+# word transactions in the end when we are already almost certain that we
+# have an LM92 chip or compatible.
 sub lm92_detect
 {
   my ($chip, $file, $addr) = @_;
 
   my $conf = i2c_smbus_read_byte_data($file, 0x01);
-  my $hyst = i2c_smbus_read_word_data($file, 0x02);
-  my $crit = i2c_smbus_read_word_data($file, 0x03);
-  my $low = i2c_smbus_read_word_data($file, 0x04);
-  my $high = i2c_smbus_read_word_data($file, 0x05);
+  my $hyst = i2c_smbus_read_byte_data($file, 0x02);
+  my $crit = i2c_smbus_read_byte_data($file, 0x03);
+  my $low = i2c_smbus_read_byte_data($file, 0x04);
+  my $high = i2c_smbus_read_byte_data($file, 0x05);
 
   return if $conf == 0 and $hyst == 0 and $crit == 0
         and $low == 0 and $high == 0;
 
-  return if $chip == 0
-        and i2c_smbus_read_word_data($file, 0x07) != 0x0180;
-  
+  # Unused bits
   return if ($chip == 0 || $chip == 1)
         and ($conf & 0xE0);
 
-  for (my $i = 0; $i < 8; $i++) {
-    return if i2c_smbus_read_byte_data($file, $i*16+0x01) != $conf;
-    return if i2c_smbus_read_word_data($file, $i*16+0x02) != $hyst;
-    return if i2c_smbus_read_word_data($file, $i*16+0x03) != $crit;
-    return if i2c_smbus_read_word_data($file, $i*16+0x04) != $low;
-    return if i2c_smbus_read_word_data($file, $i*16+0x05) != $high;
+  for (my $i = 0; $i <= 240; $i += 16) {
+    return if i2c_smbus_read_byte_data($file, $i + 0x01) != $conf;
+    return if i2c_smbus_read_byte_data($file, $i + 0x02) != $hyst;
+    return if i2c_smbus_read_byte_data($file, $i + 0x03) != $crit;
+    return if i2c_smbus_read_byte_data($file, $i + 0x04) != $low;
+    return if i2c_smbus_read_byte_data($file, $i + 0x05) != $high;
   }
   
+  return if $chip == 0
+        and i2c_smbus_read_word_data($file, 0x07) != 0x0180;
+
+  # Make sure the chip supports SMBus read word transactions
+  $hyst = i2c_smbus_read_word_data($file, 0x02);
+  return if $hyst < 0;
+  $crit = i2c_smbus_read_word_data($file, 0x03);
+  return if $crit < 0;
+  $low = i2c_smbus_read_word_data($file, 0x04);
+  return if $low < 0;
+  $high = i2c_smbus_read_word_data($file, 0x05);
+  return if $high < 0;
+
   foreach my $temp ($hyst, $crit, $low, $high) {
     return if $chip == 2 and ($temp & 0x7F00);
     return if $chip != 2 and ($temp & 0x0700);
@@ -3763,23 +3789,38 @@ sub lm92_detect
 #   0xAA: Temperature
 #   0xA1: High limit
 #   0xA2: Low limit
+#   0xA8: Counter
+#   0xA9: Slope
 #   0xAC: Configuration
 # Detection is weak. We check if bit 4 (NVB) is clear, because it is
 # unlikely to be set (would mean that EEPROM is currently being accessed).
-# Temperature checkings will hopefully prevent LM75 or other chips from
-# being detected as a DS1621.
+# We also check the value of the counter and slope registers, the datasheet
+# doesn't mention the possible values but the conversion formula together
+# with experimental evidence suggest possible sanity checks.
+# Not all devices enjoy SMBus read word transactions, so we do as much as
+# possible with read byte transactions first, and only use read word
+# transactions second.
 sub ds1621_detect
 {
-  my $i;
   my ($file,$addr) = @_;
+
+  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 & 0x7f00);
   my $high = i2c_smbus_read_word_data($file,0xA1);
+  return if $high < 0 || ($high & 0x7f00);
   my $low = i2c_smbus_read_word_data($file,0xA2);
-  return if ($temp | $high | $low) & 0x7F00;
-  my $conf = i2c_smbus_read_byte_data($file,0xAC);
+  return if $low < 0 || ($low & 0x7f00);
+
   return if ($temp == 0 && $high == 0 && $low == 0 && $conf == 0);
-  return 3 if ($conf & 0x10) == 0x00;
-  return;
+
+  return 3;
 }
 
 # $_[0]: A reference to the file descriptor to access this chip.