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 at linux-fr.org> --- Documentation/hwmon/w83781d | 37 +++++++++++++++++++++++++++++++++++-- 1 file changed, 35 insertions(+), 2 deletions(-) --- linux-2.6.27-rc8.orig/Documentation/hwmon/w83781d 2008-04-17 04:49:44.000000000 +0200 +++ linux-2.6.27-rc8/Documentation/hwmon/w83781d 2008-10-04 13:36:02.000000000 +0200 @@ -353,7 +353,7 @@ in6=255 # PWM -Additional info about PWM on the AS99127F (may apply to other Asus +* Additional info about PWM on the AS99127F (may apply to other Asus chips as well) by Jean Delvare as of 2004-04-09: AS99127F revision 2 seems to have two PWM registers at 0x59 and 0x5A, @@ -396,7 +396,7 @@ Please contact us if you can figure out long as we don't know more, the w83781d driver doesn't handle PWM on AS99127F chips at all. -Additional info about PWM on the AS99127F rev.1 by Hector Martin: +* Additional info about PWM on the AS99127F rev.1 by Hector Martin: I've been fiddling around with the (in)famous 0x59 register and found out the following values do work as a form of coarse pwm: @@ -418,3 +418,36 @@ change. My mobo is an ASUS A7V266-E. This behavior is similar to what I got with speedfan under Windows, where 0-15% would be off, 15-2x% (can't remember the exact value) would be 70% and higher would be full on. + +* Additional info about PWM on the AS99127F rev.1 from lm-sensors + ticket #2350: + +I conducted some experiment on Asus P3B-F motherboard with AS99127F +(Ver. 1). + +I confirm that 0x59 register control the CPU_Fan Header on this +motherboard, and 0x5a register control PWR_Fan. + +In order to reduce the dependency of specific fan, the measurement is +conducted with a digital scope without fan connected. I found out that +P3B-F actually output variable DC voltage on fan header center pin, +looks like PWM is filtered on this motherboard. + +Here are some of measurements: + +0x80 20 mV +0x81 20 mV +0x82 232 mV +0x83 1.2 V +0x84 2.31 V +0x85 3.44 V +0x86 4.62 V +0x87 5.81 V +0x88 7.01 V +9x89 8.22 V +0x8a 9.42 V +0x8b 10.6 V +0x8c 11.9 V +0x8d 12.4 V +0x8e 12.4 V +0x8f 12.4 V -- Jean Delvare
