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| -rw-r--r-- | Documentation/hwmon/f71805f | 42 |
1 files changed, 38 insertions, 4 deletions
diff --git a/Documentation/hwmon/f71805f b/Documentation/hwmon/f71805f index 2ca69df669c3..bc571f99d0ee 100644 --- a/Documentation/hwmon/f71805f +++ b/Documentation/hwmon/f71805f @@ -13,8 +13,8 @@ Thanks to Denis Kieft from Barracuda Networks for the donation of a test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and for providing initial documentation. -Thanks to Kris Chen from Fintek for answering technical questions and -providing additional documentation. +Thanks to Kris Chen and Aaron Huang from Fintek for answering technical +questions and providing additional documentation. Thanks to Chris Lin from Jetway for providing wiring schematics and answering technical questions. @@ -28,8 +28,7 @@ capabilities. It can monitor up to 9 voltages (counting its own power source), 3 fans and 3 temperature sensors. This chip also has fan controlling features, using either DC or PWM, in -three different modes (one manual, two automatic). The driver doesn't -support these features yet. +three different modes (one manual, two automatic). The driver assumes that no more than one chip is present, which seems reasonable. @@ -103,3 +102,38 @@ sensor. Each channel can be used for connecting either a thermal diode or a thermistor. The driver reports the currently selected mode, but doesn't allow changing it. In theory, the BIOS should have configured everything properly. + + +Fan Control +----------- + +Both PWM (pulse-width modulation) and DC fan speed control methods are +supported. The right one to use depends on external circuitry on the +motherboard, so the driver assumes that the BIOS set the method +properly. The driver will report the method, but won't let you change +it. + +When the PWM method is used, you can select the operating frequency, +from 187.5 kHz (default) to 31 Hz. The best frequency depends on the +fan model. As a rule of thumb, lower frequencies seem to give better +control, but may generate annoying high-pitch noise. Fintek recommends +not going below 1 kHz, as the fan tachometers get confused by lower +frequencies as well. + +When the DC method is used, Fintek recommends not going below 5 V, which +corresponds to a pwm value of 106 for the driver. The driver doesn't +enforce this limit though. + +Three different fan control modes are supported: + +* Manual mode + You ask for a specific PWM duty cycle or DC voltage. + +* Fan speed mode + You ask for a specific fan speed. This mode assumes that pwm1 + corresponds to fan1, pwm2 to fan2 and pwm3 to fan3. + +* Temperature mode + You define 3 temperature/fan speed trip points, and the fan speed is + adjusted depending on the measured temperature, using interpolation. + This mode is not yet supported by the driver. |