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Document the different fan control methods, list their options, and give some hints for best results. Signed-off-by: Jean Delvare <khali@linux-fr.org>
140 lines
5.1 KiB
Plaintext
140 lines
5.1 KiB
Plaintext
Kernel driver f71805f
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=====================
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Supported chips:
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* Fintek F71805F/FG
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Prefix: 'f71805f'
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Addresses scanned: none, address read from Super I/O config space
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Datasheet: Provided by Fintek on request
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Author: Jean Delvare <khali@linux-fr.org>
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Thanks to Denis Kieft from Barracuda Networks for the donation of a
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test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and
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for providing initial documentation.
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Thanks to Kris Chen and Aaron Huang from Fintek for answering technical
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questions and providing additional documentation.
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Thanks to Chris Lin from Jetway for providing wiring schematics and
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answering technical questions.
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Description
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-----------
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The Fintek F71805F/FG Super I/O chip includes complete hardware monitoring
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capabilities. It can monitor up to 9 voltages (counting its own power
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source), 3 fans and 3 temperature sensors.
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This chip also has fan controlling features, using either DC or PWM, in
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three different modes (one manual, two automatic).
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The driver assumes that no more than one chip is present, which seems
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reasonable.
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Voltage Monitoring
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------------------
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Voltages are sampled by an 8-bit ADC with a LSB of 8 mV. The supported
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range is thus from 0 to 2.040 V. Voltage values outside of this range
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need external resistors. An exception is in0, which is used to monitor
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the chip's own power source (+3.3V), and is divided internally by a
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factor 2.
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The two LSB of the voltage limit registers are not used (always 0), so
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you can only set the limits in steps of 32 mV (before scaling).
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The wirings and resistor values suggested by Fintek are as follow:
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pin expected
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name use R1 R2 divider raw val.
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in0 VCC VCC3.3V int. int. 2.00 1.65 V
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in1 VIN1 VTT1.2V 10K - 1.00 1.20 V
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in2 VIN2 VRAM 100K 100K 2.00 ~1.25 V (1)
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in3 VIN3 VCHIPSET 47K 100K 1.47 2.24 V (2)
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in4 VIN4 VCC5V 200K 47K 5.25 0.95 V
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in5 VIN5 +12V 200K 20K 11.00 1.05 V
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in6 VIN6 VCC1.5V 10K - 1.00 1.50 V
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in7 VIN7 VCORE 10K - 1.00 ~1.40 V (1)
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in8 VIN8 VSB5V 200K 47K 1.00 0.95 V
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(1) Depends on your hardware setup.
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(2) Obviously not correct, swapping R1 and R2 would make more sense.
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These values can be used as hints at best, as motherboard manufacturers
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are free to use a completely different setup. As a matter of fact, the
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Jetway K8M8MS uses a significantly different setup. You will have to
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find out documentation about your own motherboard, and edit sensors.conf
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accordingly.
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Each voltage measured has associated low and high limits, each of which
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triggers an alarm when crossed.
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Fan Monitoring
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--------------
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Fan rotation speeds are reported as 12-bit values from a gated clock
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signal. Speeds down to 366 RPM can be measured. There is no theoretical
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high limit, but values over 6000 RPM seem to cause problem. The effective
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resolution is much lower than you would expect, the step between different
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register values being 10 rather than 1.
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The chip assumes 2 pulse-per-revolution fans.
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An alarm is triggered if the rotation speed drops below a programmable
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limit or is too low to be measured.
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Temperature Monitoring
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----------------------
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Temperatures are reported in degrees Celsius. Each temperature measured
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has a high limit, those crossing triggers an alarm. There is an associated
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hysteresis value, below which the temperature has to drop before the
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alarm is cleared.
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All temperature channels are external, there is no embedded temperature
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sensor. Each channel can be used for connecting either a thermal diode
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or a thermistor. The driver reports the currently selected mode, but
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doesn't allow changing it. In theory, the BIOS should have configured
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everything properly.
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Fan Control
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-----------
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Both PWM (pulse-width modulation) and DC fan speed control methods are
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supported. The right one to use depends on external circuitry on the
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motherboard, so the driver assumes that the BIOS set the method
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properly. The driver will report the method, but won't let you change
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it.
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When the PWM method is used, you can select the operating frequency,
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from 187.5 kHz (default) to 31 Hz. The best frequency depends on the
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fan model. As a rule of thumb, lower frequencies seem to give better
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control, but may generate annoying high-pitch noise. Fintek recommends
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not going below 1 kHz, as the fan tachometers get confused by lower
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frequencies as well.
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When the DC method is used, Fintek recommends not going below 5 V, which
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corresponds to a pwm value of 106 for the driver. The driver doesn't
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enforce this limit though.
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Three different fan control modes are supported:
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* Manual mode
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You ask for a specific PWM duty cycle or DC voltage.
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* Fan speed mode
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You ask for a specific fan speed. This mode assumes that pwm1
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corresponds to fan1, pwm2 to fan2 and pwm3 to fan3.
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* Temperature mode
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You define 3 temperature/fan speed trip points, and the fan speed is
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adjusted depending on the measured temperature, using interpolation.
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This mode is not yet supported by the driver.
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