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| author | Jean Delvare <khali@linux-fr.org> | 2011-03-21 17:59:36 +0100 |
|---|---|---|
| committer | Jean Delvare <khali@endymion.delvare> | 2011-03-21 17:59:36 +0100 |
| commit | e76f67b5babc65cd620d395a1fd231409808df90 (patch) | |
| tree | a5af03c47fd02f83e1a35f75a4efaf1a1f6fe5b6 /drivers | |
| parent | hwmon: (lm75) Add detection of the National Semiconductor LM75A (diff) | |
| download | linux-e76f67b5babc65cd620d395a1fd231409808df90.tar.xz linux-e76f67b5babc65cd620d395a1fd231409808df90.zip | |
hwmon: (lm75) Speed up detection
Make the LM75/LM75A device detection faster:
* Don't read the current temperature value when we don't use it.
* Check for unused bits in the configuration register as soon as we
have read its value.
* Don't use word reads, not all devices support this, and some which
don't misbehave when you try.
* Check for cycling register values every 40 register addresses
instead of every 8, it's 5 times faster and just as efficient.
Some of these improvements come straight from the user-space
sensors-detect script, so both detection routines are in line now.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Len Sorensen <lsorense@csclub.uwaterloo.ca>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/hwmon/lm75.c | 40 |
1 files changed, 19 insertions, 21 deletions
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c index 638dd0586e3f..ef902d5d06ab 100644 --- a/drivers/hwmon/lm75.c +++ b/drivers/hwmon/lm75.c @@ -240,7 +240,7 @@ static int lm75_detect(struct i2c_client *new_client, { struct i2c_adapter *adapter = new_client->adapter; int i; - int cur, conf, hyst, os; + int conf, hyst, os; bool is_lm75a = 0; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | @@ -261,8 +261,10 @@ static int lm75_detect(struct i2c_client *new_client, register 7, and unused registers return 0xff rather than the last read value. */ - cur = i2c_smbus_read_word_data(new_client, 0); + /* Unused bits */ conf = i2c_smbus_read_byte_data(new_client, 1); + if (conf & 0xe0) + return -ENODEV; /* First check for LM75A */ if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) { @@ -273,33 +275,29 @@ static int lm75_detect(struct i2c_client *new_client, || i2c_smbus_read_byte_data(new_client, 6) != 0xff) return -ENODEV; is_lm75a = 1; - hyst = i2c_smbus_read_word_data(new_client, 2); - os = i2c_smbus_read_word_data(new_client, 3); + hyst = i2c_smbus_read_byte_data(new_client, 2); + os = i2c_smbus_read_byte_data(new_client, 3); } else { /* Traditional style LM75 detection */ /* Unused addresses */ - hyst = i2c_smbus_read_word_data(new_client, 2); - if (i2c_smbus_read_word_data(new_client, 4) != hyst - || i2c_smbus_read_word_data(new_client, 5) != hyst - || i2c_smbus_read_word_data(new_client, 6) != hyst - || i2c_smbus_read_word_data(new_client, 7) != hyst) + hyst = i2c_smbus_read_byte_data(new_client, 2); + if (i2c_smbus_read_byte_data(new_client, 4) != hyst + || i2c_smbus_read_byte_data(new_client, 5) != hyst + || i2c_smbus_read_byte_data(new_client, 6) != hyst + || i2c_smbus_read_byte_data(new_client, 7) != hyst) return -ENODEV; - os = i2c_smbus_read_word_data(new_client, 3); - if (i2c_smbus_read_word_data(new_client, 4) != os - || i2c_smbus_read_word_data(new_client, 5) != os - || i2c_smbus_read_word_data(new_client, 6) != os - || i2c_smbus_read_word_data(new_client, 7) != os) + os = i2c_smbus_read_byte_data(new_client, 3); + if (i2c_smbus_read_byte_data(new_client, 4) != os + || i2c_smbus_read_byte_data(new_client, 5) != os + || i2c_smbus_read_byte_data(new_client, 6) != os + || i2c_smbus_read_byte_data(new_client, 7) != os) return -ENODEV; } - /* Unused bits */ - if (conf & 0xe0) - return -ENODEV; - /* Addresses cycling */ - for (i = 8; i < 0xff; i += 8) { + for (i = 8; i <= 248; i += 40) { if (i2c_smbus_read_byte_data(new_client, i + 1) != conf - || i2c_smbus_read_word_data(new_client, i + 2) != hyst - || i2c_smbus_read_word_data(new_client, i + 3) != os) + || i2c_smbus_read_byte_data(new_client, i + 2) != hyst + || i2c_smbus_read_byte_data(new_client, i + 3) != os) return -ENODEV; if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7) != LM75A_ID) |