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authorPhil Endecott <kernel@chezphil.org>2007-06-29 09:19:14 +0200
committerMark M. Hoffman <mhoffman@lightlink.com>2007-07-19 14:22:15 -0400
commitaba5073d3f4c928c89c483d85f8cff7cc9aa3312 (patch)
treec966ca4de6e14d4edbb7232b3dcef3fb7e114b7f /Documentation
parent158ce07564b68d4215b9560213a089d6f7c5a4ea (diff)
hwmon/f71805f: Add temperature-tracking fan control mode
Add support for the "temperature mode" fan speed control. In this mode, the user can define 3 temperature/speed trip points, and the chip will set the speed automatically according to the temperature changes. Signed-off-by: Phil Endecott <kernel@chezphil.org> Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/hwmon/f71805f35
1 files changed, 22 insertions, 13 deletions
diff --git a/Documentation/hwmon/f71805f b/Documentation/hwmon/f71805f
index bfd0f154959..94e0d2cbd3d 100644
--- a/Documentation/hwmon/f71805f
+++ b/Documentation/hwmon/f71805f
@@ -5,11 +5,11 @@ Supported chips:
* Fintek F71805F/FG
Prefix: 'f71805f'
Addresses scanned: none, address read from Super I/O config space
- Datasheet: Provided by Fintek on request
+ Datasheet: Available from the Fintek website
* Fintek F71872F/FG
Prefix: 'f71872f'
Addresses scanned: none, address read from Super I/O config space
- Datasheet: Provided by Fintek on request
+ Datasheet: Available from the Fintek website
Author: Jean Delvare <khali@linux-fr.org>
@@ -128,7 +128,9 @@ 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
+control, but may generate annoying high-pitch noise. So a frequency just
+above the audible range, such as 25 kHz, may be a good choice; if this
+doesn't give you good linear control, try reducing it. Fintek recommends
not going below 1 kHz, as the fan tachometers get confused by lower
frequencies as well.
@@ -136,16 +138,23 @@ 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:
+Three different fan control modes are supported; the mode number is written
+to the pwm<n>_enable file.
-* Manual mode
- You ask for a specific PWM duty cycle or DC voltage.
+* 1: Manual mode
+ You ask for a specific PWM duty cycle or DC voltage by writing to the
+ pwm<n> file.
-* 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.
+* 2: Temperature mode
+ You define 3 temperature/fan speed trip points using the
+ pwm<n>_auto_point<m>_temp and _fan files. These define a staircase
+ relationship between temperature and fan speed with two additional points
+ interpolated between the values that you define. When the temperature
+ is below auto_point1_temp the fan is switched off.
-* 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.
+* 3: Fan speed mode
+ You ask for a specific fan speed by writing to the fan<n>_target file.
+
+Both of the automatic modes require that pwm1 corresponds to fan1, pwm2 to
+fan2 and pwm3 to fan3. Temperature mode also requires that temp1 corresponds
+to pwm1 and fan1, etc.