hwmon: (w83781d) Additional information about AS99127F PWM
This information was provided in lm-sensors ticket #2350: http://www.lm-sensors.org/ticket/2350 This is IMHO still not enough to be able to safely implement fan control support for the AS99127F, but this is valuable information so I am adding it to the documentation. Signed-off-by: Jean Delvare <khali@linux-fr.org>
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@ -353,7 +353,7 @@ in6=255
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# PWM
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Additional info about PWM on the AS99127F (may apply to other Asus
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* Additional info about PWM on the AS99127F (may apply to other Asus
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chips as well) by Jean Delvare as of 2004-04-09:
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AS99127F revision 2 seems to have two PWM registers at 0x59 and 0x5A,
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@ -396,7 +396,7 @@ Please contact us if you can figure out how it is supposed to work. As
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long as we don't know more, the w83781d driver doesn't handle PWM on
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AS99127F chips at all.
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Additional info about PWM on the AS99127F rev.1 by Hector Martin:
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* Additional info about PWM on the AS99127F rev.1 by Hector Martin:
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I've been fiddling around with the (in)famous 0x59 register and
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found out the following values do work as a form of coarse pwm:
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@ -418,3 +418,36 @@ change.
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My mobo is an ASUS A7V266-E. This behavior is similar to what I got
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with speedfan under Windows, where 0-15% would be off, 15-2x% (can't
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remember the exact value) would be 70% and higher would be full on.
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* Additional info about PWM on the AS99127F rev.1 from lm-sensors
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ticket #2350:
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I conducted some experiment on Asus P3B-F motherboard with AS99127F
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(Ver. 1).
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I confirm that 0x59 register control the CPU_Fan Header on this
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motherboard, and 0x5a register control PWR_Fan.
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In order to reduce the dependency of specific fan, the measurement is
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conducted with a digital scope without fan connected. I found out that
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P3B-F actually output variable DC voltage on fan header center pin,
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looks like PWM is filtered on this motherboard.
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Here are some of measurements:
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0x80 20 mV
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0x81 20 mV
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0x82 232 mV
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0x83 1.2 V
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0x84 2.31 V
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0x85 3.44 V
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0x86 4.62 V
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0x87 5.81 V
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0x88 7.01 V
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9x89 8.22 V
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0x8a 9.42 V
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0x8b 10.6 V
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0x8c 11.9 V
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0x8d 12.4 V
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0x8e 12.4 V
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0x8f 12.4 V
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