Commit e76f67b5babc65cd620d395a1fd231409808df90
Committed by
Jean Delvare
Jean Delvare
1 parent
05e82fe40f
Exists in
master
and in
4 other branches
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>
Showing 1 changed file with 19 additions and 21 deletions Side-by-side Diff
drivers/hwmon/lm75.c
| ... | ... | @@ -240,7 +240,7 @@ |
| 240 | 240 | { |
| 241 | 241 | struct i2c_adapter *adapter = new_client->adapter; |
| 242 | 242 | int i; |
| 243 | - int cur, conf, hyst, os; | |
| 243 | + int conf, hyst, os; | |
| 244 | 244 | bool is_lm75a = 0; |
| 245 | 245 | |
| 246 | 246 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | |
| 247 | 247 | |
| ... | ... | @@ -261,8 +261,10 @@ |
| 261 | 261 | register 7, and unused registers return 0xff rather than the |
| 262 | 262 | last read value. */ |
| 263 | 263 | |
| 264 | - cur = i2c_smbus_read_word_data(new_client, 0); | |
| 264 | + /* Unused bits */ | |
| 265 | 265 | conf = i2c_smbus_read_byte_data(new_client, 1); |
| 266 | + if (conf & 0xe0) | |
| 267 | + return -ENODEV; | |
| 266 | 268 | |
| 267 | 269 | /* First check for LM75A */ |
| 268 | 270 | if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) { |
| 269 | 271 | |
| 270 | 272 | |
| 271 | 273 | |
| 272 | 274 | |
| 273 | 275 | |
| ... | ... | @@ -273,33 +275,29 @@ |
| 273 | 275 | || i2c_smbus_read_byte_data(new_client, 6) != 0xff) |
| 274 | 276 | return -ENODEV; |
| 275 | 277 | is_lm75a = 1; |
| 276 | - hyst = i2c_smbus_read_word_data(new_client, 2); | |
| 277 | - os = i2c_smbus_read_word_data(new_client, 3); | |
| 278 | + hyst = i2c_smbus_read_byte_data(new_client, 2); | |
| 279 | + os = i2c_smbus_read_byte_data(new_client, 3); | |
| 278 | 280 | } else { /* Traditional style LM75 detection */ |
| 279 | 281 | /* Unused addresses */ |
| 280 | - hyst = i2c_smbus_read_word_data(new_client, 2); | |
| 281 | - if (i2c_smbus_read_word_data(new_client, 4) != hyst | |
| 282 | - || i2c_smbus_read_word_data(new_client, 5) != hyst | |
| 283 | - || i2c_smbus_read_word_data(new_client, 6) != hyst | |
| 284 | - || i2c_smbus_read_word_data(new_client, 7) != hyst) | |
| 282 | + hyst = i2c_smbus_read_byte_data(new_client, 2); | |
| 283 | + if (i2c_smbus_read_byte_data(new_client, 4) != hyst | |
| 284 | + || i2c_smbus_read_byte_data(new_client, 5) != hyst | |
| 285 | + || i2c_smbus_read_byte_data(new_client, 6) != hyst | |
| 286 | + || i2c_smbus_read_byte_data(new_client, 7) != hyst) | |
| 285 | 287 | return -ENODEV; |
| 286 | - os = i2c_smbus_read_word_data(new_client, 3); | |
| 287 | - if (i2c_smbus_read_word_data(new_client, 4) != os | |
| 288 | - || i2c_smbus_read_word_data(new_client, 5) != os | |
| 289 | - || i2c_smbus_read_word_data(new_client, 6) != os | |
| 290 | - || i2c_smbus_read_word_data(new_client, 7) != os) | |
| 288 | + os = i2c_smbus_read_byte_data(new_client, 3); | |
| 289 | + if (i2c_smbus_read_byte_data(new_client, 4) != os | |
| 290 | + || i2c_smbus_read_byte_data(new_client, 5) != os | |
| 291 | + || i2c_smbus_read_byte_data(new_client, 6) != os | |
| 292 | + || i2c_smbus_read_byte_data(new_client, 7) != os) | |
| 291 | 293 | return -ENODEV; |
| 292 | 294 | } |
| 293 | 295 | |
| 294 | - /* Unused bits */ | |
| 295 | - if (conf & 0xe0) | |
| 296 | - return -ENODEV; | |
| 297 | - | |
| 298 | 296 | /* Addresses cycling */ |
| 299 | - for (i = 8; i < 0xff; i += 8) { | |
| 297 | + for (i = 8; i <= 248; i += 40) { | |
| 300 | 298 | if (i2c_smbus_read_byte_data(new_client, i + 1) != conf |
| 301 | - || i2c_smbus_read_word_data(new_client, i + 2) != hyst | |
| 302 | - || i2c_smbus_read_word_data(new_client, i + 3) != os) | |
| 299 | + || i2c_smbus_read_byte_data(new_client, i + 2) != hyst | |
| 300 | + || i2c_smbus_read_byte_data(new_client, i + 3) != os) | |
| 303 | 301 | return -ENODEV; |
| 304 | 302 | if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7) |
| 305 | 303 | != LM75A_ID) |