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- Kernel driver g760a
- ===================
- Supported chips:
- * Global Mixed-mode Technology Inc. G760A
- Prefix: 'g760a'
- Datasheet: Publicly available at the GMT website
- http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
- Author: Herbert Valerio Riedel <hvr@gnu.org>
- Description
- -----------
- The GMT G760A Fan Speed PWM Controller is connected directly to a fan
- and performs closed-loop control of the fan speed.
- The fan speed is programmed by setting the period via 'pwm1' of two
- consecutive speed pulses. The period is defined in terms of clock
- cycle counts of an assumed 32kHz clock source.
- Setting a period of 0 stops the fan; setting the period to 255 sets
- fan to maximum speed.
- The measured fan rotation speed returned via 'fan1_input' is derived
- from the measured speed pulse period by assuming again a 32kHz clock
- source and a 2 pulse-per-revolution fan.
- The 'alarms' file provides access to the two alarm bits provided by
- the G760A chip's status register: Bit 0 is set when the actual fan
- speed differs more than 20% with respect to the programmed fan speed;
- bit 1 is set when fan speed is below 1920 RPM.
- The g760a driver will not update its values more frequently than every
- other second; reading them more often will do no harm, but will return
- 'old' values.
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