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authorMichael Arndt <michael@scriptkiller.de>2013-02-17 14:51:20 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-02-18 16:55:24 -0500
commit29e5507ae4ab34397f538f06b7070c81a4e4a2bf (patch)
tree6ac51b0113c909e2e5f7fabe8fdabc33bfee04da /Documentation/w1
parent9c95bb6f25ff802081125f24bf0c756252fa27b2 (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_therm13
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
34precision (which would also reduce the conversion time). 34precision (which would also reduce the conversion time).
35 35
36The module parameter strong_pullup can be set to 0 to disable the 36The module parameter strong_pullup can be set to 0 to disable the
37strong pullup or 1 to enable. If enabled the 5V strong pullup will be 37strong pullup, 1 to enable autodetection or 2 to force strong pullup.
38enabled when the conversion is taking place provided the master driver 38In case of autodetection, the driver will use the "READ POWER SUPPLY"
39must support the strong pullup (or it falls back to a pullup 39command to check if there are pariste powered devices on the bus.
40If so, it will activate the master's strong pullup.
41In case the detection of parasite devices using this command fails
42(seems to be the case with some DS18S20) the strong pullup can
43be force-enabled.
44If the strong pullup is enabled, the master's strong pullup will be
45driven when the conversion is taking place, provided the master driver
46does support the strong pullup (or it falls back to a pullup
40resistor). The DS18b20 temperature sensor specification lists a 47resistor). The DS18b20 temperature sensor specification lists a
41maximum current draw of 1.5mA and that a 5k pullup resistor is not 48maximum current draw of 1.5mA and that a 5k pullup resistor is not
42sufficient. The strong pullup is designed to provide the additional 49sufficient. The strong pullup is designed to provide the additional