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Updating the fan speeds according to the manufacturer's specs. The fan vendor recommends that the minimum fan speed be a 20% duty cycle. Since the built-in fan controller has a tach-based feedback loop, I'm using the RPM value instead of the duty cycle (20% is 2286 RPM, according to the vendor). The vendor also wants a 30% duty cycle to start turning, but the built-in fan controller provides support for fast-start too. The controller's minimum fast-start duty cycle is 50%, but it also has a programmable number of revolutions that it will wait before backing off. Holding my ear down close to the fans while they start and stop, it seems that the minimum 2 revolution start period is sufficient and provides the least noise. Of course, since I've never had any problems starting the fans directly at 1000 RPM this noise is a little more noticeable than that. It's quite possible that the built-in controller is smart enough to make 1000 RPM work by bumping the duty cycle up until the fans turn even if the fans don't like it. BUG=chrome-os-partner:32892 BRANCH=ToT,samus TEST=manual Listen closely and run the EC console "faninfo" command to see the fans start and stop as the system boots and idles. Change-Id: I47c9e7cef3f9f4bd815a13032fe10234decd62ed Signed-off-by: Bill Richardson <wfrichar@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/224830 Reviewed-by: Randall Spangler <rspangler@chromium.org>
92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Fan control module for Chrome EC */
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#ifndef __CROS_EC_FAN_H
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#define __CROS_EC_FAN_H
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/* Characteristic of each physical fan */
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struct fan_t {
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unsigned int flags;
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int rpm_min;
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int rpm_max;
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/* Hardware channel number (the meaning is chip-specific) */
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int ch;
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/* Active-high power_good input GPIO, or -1 if none */
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int pgood_gpio;
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/* Active-high power_enable output GPIO, or -1 if none */
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int enable_gpio;
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};
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/* Values for .flags field */
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/* Enable automatic RPM control using tach input */
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#define FAN_USE_RPM_MODE (1 << 0)
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/* Require a higher duty cycle to start up than to keep running */
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#define FAN_USE_FAST_START (1 << 1)
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/* The list of fans is instantiated in board.c. */
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extern const struct fan_t fans[];
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/**
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* Set the amount of active cooling needed. The thermal control task will call
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* this frequently, and the fan control logic will attempt to provide it.
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*
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* @param fan Fan number (index into fans[])
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* @param pct Percentage of cooling effort needed (0 - 100)
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*/
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void fan_set_percent_needed(int fan, int pct);
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/**
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* This function translates the percentage of cooling needed into a target RPM.
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* The default implementation should be sufficient for most needs, but
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* individual boards may provide a custom version if needed (see config.h).
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*
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* @param fan Fan number (index into fans[])
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* @param pct Percentage of cooling effort needed (always in [0,100])
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* Return Target RPM for fan
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*/
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int fan_percent_to_rpm(int fan, int pct);
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/**
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* These functions require chip-specific implementations.
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*/
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/* Enable/Disable the fan controller */
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void fan_set_enabled(int ch, int enabled);
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int fan_get_enabled(int ch);
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/* Fixed pwm duty cycle (0-100%) */
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void fan_set_duty(int ch, int percent);
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int fan_get_duty(int ch);
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/* Enable/Disable automatic RPM control using tach feedback */
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void fan_set_rpm_mode(int ch, int rpm_mode);
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int fan_get_rpm_mode(int ch);
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/* Set the target for the automatic RPM control */
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void fan_set_rpm_target(int ch, int rpm);
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int fan_get_rpm_actual(int ch);
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int fan_get_rpm_target(int ch);
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/* Is the fan stalled when it shouldn't be? */
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int fan_is_stalled(int ch);
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/* How is the automatic RPM control doing? */
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enum fan_status {
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FAN_STATUS_STOPPED = 0,
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FAN_STATUS_CHANGING = 1,
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FAN_STATUS_LOCKED = 2,
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FAN_STATUS_FRUSTRATED = 3
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};
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enum fan_status fan_get_status(int ch);
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/* Initialize the HW according to the desired flags */
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void fan_channel_setup(int ch, unsigned int flags);
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#endif /* __CROS_EC_FAN_H */
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