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| author | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2013-03-18 06:40:50 +0400 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2013-03-18 06:40:50 +0400 |
| commit | 688d794c4c3f8b08c814381ee2edd3ede5856056 (patch) | |
| tree | ef680add71e2a9588d07d8b594edbc1b5cd127d7 /Documentation/w1/slaves/w1_therm | |
| parent | 16142655269aaf580488e074eabfdcf0fb4e3687 (diff) | |
| parent | a937536b868b8369b98967929045f1df54234323 (diff) | |
| download | linux-688d794c4c3f8b08c814381ee2edd3ede5856056.tar.xz | |
Merge tag 'v3.9-rc3' into next
Merge with mainline to bring in module_platform_driver_probe() and
devm_ioremap_resource().
Diffstat (limited to 'Documentation/w1/slaves/w1_therm')
| -rw-r--r-- | Documentation/w1/slaves/w1_therm | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm index 874a8ca93feb..cc62a95e4776 100644 --- a/Documentation/w1/slaves/w1_therm +++ b/Documentation/w1/slaves/w1_therm @@ -34,9 +34,16 @@ currently supported. The driver also doesn't support reduced precision (which would also reduce the conversion time). The module parameter strong_pullup can be set to 0 to disable the -strong pullup or 1 to enable. If enabled the 5V strong pullup will be -enabled when the conversion is taking place provided the master driver -must support the strong pullup (or it falls back to a pullup +strong pullup, 1 to enable autodetection or 2 to force strong pullup. +In case of autodetection, the driver will use the "READ POWER SUPPLY" +command to check if there are pariste powered devices on the bus. +If so, it will activate the master's strong pullup. +In case the detection of parasite devices using this command fails +(seems to be the case with some DS18S20) the strong pullup can +be force-enabled. +If the strong pullup is enabled, the master's strong pullup will be +driven when the conversion is taking place, provided the master driver +does support the strong pullup (or it falls back to a pullup resistor). The DS18b20 temperature sensor specification lists a maximum current draw of 1.5mA and that a 5k pullup resistor is not sufficient. The strong pullup is designed to provide the additional |