diff options
author | Michael Arndt <michael@scriptkiller.de> | 2013-02-17 14:51:20 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-18 16:55:24 -0500 |
commit | 29e5507ae4ab34397f538f06b7070c81a4e4a2bf (patch) | |
tree | 6ac51b0113c909e2e5f7fabe8fdabc33bfee04da /Documentation/w1 | |
parent | 9c95bb6f25ff802081125f24bf0c756252fa27b2 (diff) |
w1: w1_therm: Add force-pullup option for "broken" sensors
Signed-off-by: Michael Arndt <michael@scriptkiller.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/w1')
-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 | |||
34 | precision (which would also reduce the conversion time). | 34 | precision (which would also reduce the conversion time). |
35 | 35 | ||
36 | The module parameter strong_pullup can be set to 0 to disable the | 36 | The module parameter strong_pullup can be set to 0 to disable the |
37 | strong pullup or 1 to enable. If enabled the 5V strong pullup will be | 37 | strong pullup, 1 to enable autodetection or 2 to force strong pullup. |
38 | enabled when the conversion is taking place provided the master driver | 38 | In case of autodetection, the driver will use the "READ POWER SUPPLY" |
39 | must support the strong pullup (or it falls back to a pullup | 39 | command to check if there are pariste powered devices on the bus. |
40 | If so, it will activate the master's strong pullup. | ||
41 | In case the detection of parasite devices using this command fails | ||
42 | (seems to be the case with some DS18S20) the strong pullup can | ||
43 | be force-enabled. | ||
44 | If the strong pullup is enabled, the master's strong pullup will be | ||
45 | driven when the conversion is taking place, provided the master driver | ||
46 | does support the strong pullup (or it falls back to a pullup | ||
40 | resistor). The DS18b20 temperature sensor specification lists a | 47 | resistor). The DS18b20 temperature sensor specification lists a |
41 | maximum current draw of 1.5mA and that a 5k pullup resistor is not | 48 | maximum current draw of 1.5mA and that a 5k pullup resistor is not |
42 | sufficient. The strong pullup is designed to provide the additional | 49 | sufficient. The strong pullup is designed to provide the additional |