fan: Replace interpolation, smoothing with stepping

Fan noise is one of the top complaints reported. The existing
interpolation and smoothing logic has not sufficiently addressed the
issues with fans changing speeds too quickly in response to rapid
changes in thermals (particularly from PECI).

This behavior can be observed by with very basic tasks, such as:

- Powering on a system and logging into GNOME
- Starting a GUI application such as Firefox

Replace them with a fixed step update per event interval. Fans now have
a maximum amount they change change over time (3.9%/sec) as they move
towards a target duty.

Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/board/system76/common/acpi.c

@@ -162,13 +162,13 @@ uint8_t acpi_read(uint8_t addr) {
 
         ACPI_8(0xCC, sci_extra);
 
-        ACPI_8(0xCE, FAN1_PWM);
+        ACPI_8(0xCE, fan1_pwm_actual);
         ACPI_16(0xD0, fan1_rpm);
 #if CONFIG_HAVE_DGPU
         ACPI_8(0xCD, dgpu_temp);
 #endif // CONFIG_HAVE_DGPU
 #ifdef FAN2_PWM
-        ACPI_8(0xCF, FAN2_PWM);
+        ACPI_8(0xCF, fan2_pwm_actual);
         ACPI_16(0xD2, fan2_rpm);
 #endif // FAN2_PWM
 

src/board/system76/common/fan.c

@@ -10,10 +10,12 @@
 
 bool fan_max = false;
 
-static uint8_t last_fan1_duty = 0;
+uint8_t fan1_pwm_actual = 0;
-static uint8_t last_fan2_duty = 0;
+uint8_t fan1_pwm_target = 0;
-
 uint16_t fan1_rpm = 0;
+
+uint8_t fan2_pwm_actual = 0;
+uint8_t fan2_pwm_target = 0;
 uint16_t fan2_rpm = 0;
 
 #define TACH_FREQ (CONFIG_CLOCK_FREQ_KHZ * 1000UL)
@@ -27,16 +29,10 @@ uint16_t fan2_rpm = 0;
 
 #define FAN_POINT(T, D) { .temp = (int16_t)(T), .duty = PWM_DUTY(D) }
 
-#if SMOOTH_FANS != 0
+#ifndef FAN1_PWM_MIN
-#define MAX_JUMP_UP ((MAX_FAN_SPEED - MIN_FAN_SPEED) / (uint8_t)SMOOTH_FANS_UP)
+#define FAN1_PWM_MIN 0
-#define MAX_JUMP_DOWN ((MAX_FAN_SPEED - MIN_FAN_SPEED) / (uint8_t)SMOOTH_FANS_DOWN)
-#else
-#define MAX_JUMP_UP (MAX_FAN_SPEED - MIN_FAN_SPEED)
-#define MAX_JUMP_DOWN (MAX_FAN_SPEED - MIN_FAN_SPEED)
 #endif
 
-#define MIN_SPEED_TO_SMOOTH PWM_DUTY(SMOOTH_FANS_MIN)
-
 // Fan speed is the lowest requested over HEATUP seconds
 #ifndef BOARD_FAN1_HEATUP
 #define BOARD_FAN1_HEATUP 4
@@ -67,11 +63,15 @@ static const struct Fan __code FAN1 = {
     .heatup_size = ARRAY_SIZE(FAN1_HEATUP),
     .cooldown = FAN1_COOLDOWN,
     .cooldown_size = ARRAY_SIZE(FAN1_COOLDOWN),
-    .interpolate = SMOOTH_FANS != 0,
+    .pwm_min = PWM_DUTY(FAN1_PWM_MIN),
 };
 
 #ifdef FAN2_PWM
 
+#ifndef FAN2_PWM_MIN
+#define FAN2_PWM_MIN 0
+#endif
+
 // Fan speed is the lowest requested over HEATUP seconds
 #ifndef BOARD_FAN2_HEATUP
 #define BOARD_FAN2_HEATUP 4
@@ -102,7 +102,7 @@ static const struct Fan __code FAN2 = {
     .heatup_size = ARRAY_SIZE(FAN2_HEATUP),
     .cooldown = FAN2_COOLDOWN,
     .cooldown_size = ARRAY_SIZE(FAN2_COOLDOWN),
-    .interpolate = SMOOTH_FANS != 0,
+    .pwm_min = PWM_DUTY(FAN2_PWM_MIN),
 };
 
 #endif // FAN2_PWM
@@ -112,8 +112,6 @@ void fan_reset(void) {
     fan_max = false;
 }
 
-// Get duty cycle based on temperature, adapted from
-// https://github.com/pop-os/system76-power/blob/master/src/fan.rs
 static uint8_t fan_duty(const struct Fan *const fan, int16_t temp) {
     for (uint8_t i = 0; i < fan->points_size; i++) {
         const struct FanPoint *cur = &fan->points[i];
@@ -127,20 +125,7 @@ static uint8_t fan_duty(const struct Fan *const fan, int16_t temp) {
                 return 0;
             } else {
                 const struct FanPoint *prev = &fan->points[i - 1];
-
+                return prev->duty;
-                if (fan->interpolate) {
-                    // If in between current temp and previous temp, interpolate
-                    if (temp > prev->temp) {
-                        int16_t dtemp = (cur->temp - prev->temp);
-                        int16_t dduty = ((int16_t)cur->duty) - ((int16_t)prev->duty);
-                        return (uint8_t)(
-                            ((int16_t)prev->duty) +
-                            ((temp - prev->temp) * dduty) / dtemp
-                        );
-                    }
-                } else {
-                    return prev->duty;
-                }
             }
         }
     }
@@ -149,38 +134,6 @@ static uint8_t fan_duty(const struct Fan *const fan, int16_t temp) {
     return CTR0;
 }
 
-static uint8_t fan_smooth(uint8_t last_duty, uint8_t duty) {
-    uint8_t next_duty = duty;
-
-    // ramping down
-    if (duty < last_duty) {
-        // out of bounds (lower) safeguard
-        uint8_t smoothed = last_duty < MIN_FAN_SPEED + MAX_JUMP_DOWN
-            ? MIN_FAN_SPEED
-            : last_duty - MAX_JUMP_DOWN;
-
-        // use smoothed value if above min and if smoothed is closer than raw
-        if (last_duty > MIN_SPEED_TO_SMOOTH && smoothed > duty) {
-            next_duty = smoothed;
-        }
-    }
-
-    // ramping up
-    if (duty > last_duty) {
-        // out of bounds (higher) safeguard
-        uint8_t smoothed = last_duty > MAX_FAN_SPEED - MAX_JUMP_UP
-            ? MAX_FAN_SPEED
-            : last_duty + MAX_JUMP_UP;
-
-        // use smoothed value if above min and if smoothed is closer than raw
-        if (duty > MIN_SPEED_TO_SMOOTH && smoothed < duty) {
-            next_duty = smoothed;
-        }
-    }
-
-    return next_duty;
-}
-
 static uint8_t fan_heatup(const struct Fan *const fan, uint8_t duty) {
     uint8_t lowest = duty;
 
@@ -216,17 +169,9 @@ static uint8_t fan_cooldown(const struct Fan *const fan, uint8_t duty) {
 static uint8_t fan_get_duty(const struct Fan *const fan, int16_t temp) {
     uint8_t duty;
 
-    if (power_state == POWER_STATE_S0) {
+    duty = fan_duty(fan, temp);
-        duty = fan_duty(fan, temp);
+    duty = fan_heatup(fan, duty);
-        if (fan_max) {
+    duty = fan_cooldown(fan, duty);
-            duty = CTR0;
-        } else {
-            duty = fan_heatup(fan, duty);
-            duty = fan_cooldown(fan, duty);
-        }
-    } else {
-        duty = 0;
-    }
 
     return duty;
 }
@@ -256,25 +201,69 @@ void fan_event(void) {
     int16_t sys_temp = peci_temp;
 #endif
 
-    // set FAN1 duty
+    // Fan update interval is 100ms (main.c). The event changes PWM duty
-    uint8_t fan1_duty = fan_get_duty(&FAN1, sys_temp);
+    // by 1 every interval to give a smoothing effect.
-    if (fan1_duty != FAN1_PWM) {
+
-        TRACE("FAN1 fan_duty_raw=%d\n", fan1_duty);
+    // Enabling fan max toggle and exiting S0 will cause duty to immediately
-        last_fan1_duty = fan1_duty = fan_smooth(last_fan1_duty, fan1_duty);
+    // change instead of stepping to provide the desired effects.
-        FAN1_PWM = fan_max ? MAX_FAN_SPEED : fan1_duty;
+
-        TRACE("FAN1 fan_duty_smoothed=%d\n", fan1_duty);
+    // Set FAN1 duty
+    fan1_pwm_target = fan_get_duty(&FAN1, sys_temp);
+    if (fan_max) {
+        fan1_pwm_target = CTR0;
+        fan1_pwm_actual = CTR0;
+    } else if (power_state != POWER_STATE_S0) {
+        fan1_pwm_target = 0;
+        fan1_pwm_actual = 0;
+    } else {
+        if (fan1_pwm_actual < fan1_pwm_target) {
+            if (fan1_pwm_actual < CTR0) {
+                fan1_pwm_actual++;
+                if (fan1_pwm_actual < FAN1.pwm_min) {
+                    fan1_pwm_actual = FAN1.pwm_min;
+                }
+            }
+        } else if (fan1_pwm_actual > fan1_pwm_target) {
+            if (fan1_pwm_actual > 0) {
+                fan1_pwm_actual--;
+                if (fan1_pwm_actual < FAN1.pwm_min) {
+                    fan1_pwm_actual = 0;
+                }
+            }
+        }
     }
+    TRACE("FAN1 duty=%d\n", fan1_pwm_actual);
+    FAN1_PWM = fan1_pwm_actual;
     fan1_rpm = fan_get_tach0_rpm();
 
 #ifdef FAN2_PWM
     // set FAN2 duty
-    uint8_t fan2_duty = fan_get_duty(&FAN2, sys_temp);
+    fan2_pwm_target = fan_get_duty(&FAN2, sys_temp);
-    if (fan2_duty != FAN2_PWM) {
+    if (fan_max) {
-        TRACE("FAN2 fan_duty_raw=%d\n", fan2_duty);
+        fan2_pwm_target = CTR0;
-        last_fan2_duty = fan2_duty = fan_smooth(last_fan2_duty, fan2_duty);
+        fan2_pwm_actual = CTR0;
-        FAN2_PWM = fan_max ? MAX_FAN_SPEED : fan2_duty;
+    } else if (power_state != POWER_STATE_S0) {
-        TRACE("FAN2 fan_duty_smoothed=%d\n", fan2_duty);
+        fan2_pwm_target = 0;
+        fan2_pwm_actual = 0;
+    } else {
+        if (fan2_pwm_actual < fan2_pwm_target) {
+            if (fan2_pwm_actual < CTR0) {
+                fan2_pwm_actual++;
+                if (fan2_pwm_actual < FAN2.pwm_min) {
+                    fan2_pwm_actual = FAN2.pwm_min;
+                }
+            }
+        } else if (fan2_pwm_actual > fan2_pwm_target) {
+            if (fan2_pwm_actual > 0) {
+                fan2_pwm_actual--;
+                if (fan2_pwm_actual < FAN2.pwm_min) {
+                    fan2_pwm_actual = 0;
+                }
+            }
+        }
     }
+    TRACE("FAN2 duty=%d\n", fan2_pwm_actual);
+    FAN2_PWM = fan2_pwm_actual;
     fan2_rpm = fan_get_tach1_rpm();
 #endif
 }

src/board/system76/common/include/board/fan.h

@@ -7,25 +7,6 @@
 #include <stdint.h>
 
 #define PWM_DUTY(X) ((uint8_t)(((((uint16_t)(X)) * 255) + 99) / 100))
-#define MAX_FAN_SPEED PWM_DUTY(100)
-#define MIN_FAN_SPEED PWM_DUTY(0)
-
-#ifndef SMOOTH_FANS
-#define SMOOTH_FANS 1 // default to fan smoothing
-#endif
-
-#if SMOOTH_FANS != 0
-#ifndef SMOOTH_FANS_UP
-#define SMOOTH_FANS_UP 45 // default to ~11 seconds for full ramp-up
-#endif
-#ifndef SMOOTH_FANS_DOWN
-#define SMOOTH_FANS_DOWN 100 // default to ~25 seconds for full ramp-down
-#endif
-#endif
-
-#ifndef SMOOTH_FANS_MIN
-#define SMOOTH_FANS_MIN 0 // default to smoothing all fan speed changes
-#endif
 
 struct FanPoint {
     int16_t temp;
@@ -39,14 +20,16 @@ struct Fan {
     uint8_t heatup_size;
     uint8_t *cooldown;
     uint8_t cooldown_size;
-    bool interpolate;
+    uint8_t pwm_min;
 };
 
 extern bool fan_max;
 
-// NOTE: These are used instead of the functions directly for ACPI to prevent
+extern uint8_t fan1_pwm_actual;
-// double reads of the tachometer values.
+extern uint8_t fan1_pwm_target;
 extern uint16_t fan1_rpm;
+extern uint8_t fan2_pwm_actual;
+extern uint8_t fan2_pwm_target;
 extern uint16_t fan2_rpm;
 
 void fan_reset(void);

src/board/system76/common/main.c

@@ -44,10 +44,10 @@ void serial(void) __interrupt(4) {}
 void timer_2(void) __interrupt(5) {}
 
 uint8_t main_cycle = 0;
-const uint16_t battery_interval = 1000;
+
-// update fan speed more frequently for smoother fans
+#define INTERVAL_100MS 100U
-// NOTE: event loop is longer than 100ms and maybe even longer than 250
+#define INTERVAL_250MS 250U
-const uint16_t fan_interval = SMOOTH_FANS != 0 ? 250 : 1000;
+#define INTERVAL_1SEC 1000U
 
 void init(void) {
     // Must happen first
@@ -98,8 +98,9 @@ void main(void) {
 
     INFO("System76 EC board '%s', version '%s'\n", board(), version());
 
-    systick_t last_time_battery = 0;
+    systick_t last_time_100ms = 0;
-    systick_t last_time_fan = 0;
+    systick_t last_time_250ms = 0;
+    systick_t last_time_1sec = 0;
 
     for (main_cycle = 0;; main_cycle++) {
         // NOTE: Do note use modulo to avoid expensive call to SDCC library
@@ -129,22 +130,23 @@ void main(void) {
 
         if (main_cycle == 0) {
             systick_t time = time_get();
-            // Only run the following once per interval
-            if ((time - last_time_fan) >= fan_interval) {
-                last_time_fan = time;
 
-                // Read thermal data
+            if ((time - last_time_100ms) >= INTERVAL_100MS) {
-                peci_read_temp();
+                last_time_100ms = time;
-                dgpu_read_temp();
 
                 fan_event();
             }
 
-            // Only run the following once per interval
+            if ((time - last_time_250ms) >= INTERVAL_250MS) {
-            if ((time - last_time_battery) >= battery_interval) {
+                last_time_250ms = time;
-                last_time_battery = time;
+
+                peci_read_temp();
+                dgpu_read_temp();
+            }
+
+            if ((time - last_time_1sec) >= INTERVAL_1SEC) {
+                last_time_1sec = time;
 
-                // Updates battery status
                 battery_event();
             }
         }

src/board/system76/common/scratch.c

@@ -1,14 +1,15 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
-#include <8051.h>
-#include <stdint.h>
-
 #include <board/dgpu.h>
+#include <board/fan.h>
 #include <board/smfi.h>
 #include <common/macro.h>
 #include <ec/pwm.h>
 #include <ec/scratch.h>
 
+#include <8051.h>
+#include <stdint.h>
+
 // Include scratch ROM
 uint8_t __code __at(SCRATCH_OFFSET) scratch_rom[] = {
 #include <scratch.h>

src/board/system76/common/smfi.c

@@ -13,27 +13,29 @@
 // the command is complete and the result is available. The client should only
 // read the SMFI_CMD_RES value when SMFI_CMD_CMD is set to CMD_NONE.
 
-#include <stdint.h>
+#include <board/smfi.h>
-#include <stdio.h>
-#include <string.h>
 
 #if !defined(__SCRATCH__)
-#include <board/scratch.h>
+#include <board/fan.h>
 #include <board/kbled.h>
 #include <board/kbscan.h>
+#include <board/scratch.h>
 
 #if CONFIG_SECURITY
 #include <board/security.h>
 #endif // CONFIG_SECURITY
-
 #endif // !defined(__SCRATCH__)
-#include <board/smfi.h>
+
 #include <common/command.h>
 #include <common/macro.h>
 #include <common/version.h>
 #include <ec/etwd.h>
 #include <ec/pwm.h>
 
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
 // Shared memory host semaphore
 volatile uint8_t __xdata __at(0x1022) SMHSR;
 // Host RAM window control
@@ -124,13 +126,11 @@ static enum Result cmd_print(void) {
 static enum Result cmd_fan_get(void) {
     switch (smfi_cmd[SMFI_CMD_DATA]) {
     case 1:
-        // Get duty of FAN1
+        smfi_cmd[SMFI_CMD_DATA + 1] = fan1_pwm_actual;
-        smfi_cmd[SMFI_CMD_DATA + 1] = FAN1_PWM;
         return RES_OK;
 #ifdef FAN2_PWM
     case 2:
-        // Get duty of FAN2
+        smfi_cmd[SMFI_CMD_DATA + 1] = fan2_pwm_actual;
-        smfi_cmd[SMFI_CMD_DATA + 1] = FAN2_PWM;
         return RES_OK;
 #endif
     }
@@ -143,12 +143,12 @@ static enum Result cmd_fan_set(void) {
     switch (smfi_cmd[SMFI_CMD_DATA]) {
     case 1:
         // Set duty cycle of FAN1
-        FAN1_PWM = smfi_cmd[SMFI_CMD_DATA + 1];
+        fan1_pwm_target = smfi_cmd[SMFI_CMD_DATA + 1];
         return RES_OK;
 #ifdef FAN2_PWM
     case 2:
         // Set duty cycle of FAN2
-        FAN2_PWM = smfi_cmd[SMFI_CMD_DATA + 1];
+        fan2_pwm_target = smfi_cmd[SMFI_CMD_DATA + 1];
         return RES_OK;
 #endif
     }

src/board/system76/darp10-b/board.mk

@@ -42,9 +42,8 @@ CFLAGS += \
 	-DPOWER_LIMIT_DC=45
 
 # Fan configs
-CFLAGS += -DSMOOTH_FANS_MIN=27
-
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=27
 CFLAGS += -DBOARD_FAN1_POINTS="\
 	FAN_POINT(48, 27), \
 	FAN_POINT(52, 27), \
@@ -57,6 +56,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR3
+CFLAGS += -DFAN2_PWM_MIN=27
 CFLAGS += -DBOARD_FAN2_POINTS="\
 	FAN_POINT(48, 27), \
 	FAN_POINT(52, 27), \

src/board/system76/darp10/board.mk

@@ -40,9 +40,8 @@ CFLAGS += \
 	-DPOWER_LIMIT_DC=45
 
 # Fan configs
-CFLAGS += -DSMOOTH_FANS_MIN=27
-
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=27
 CFLAGS += -DBOARD_FAN1_POINTS="\
 	FAN_POINT(48, 27), \
 	FAN_POINT(52, 27), \
@@ -55,6 +54,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR3
+CFLAGS += -DFAN2_PWM_MIN=27
 CFLAGS += -DBOARD_FAN2_POINTS="\
 	FAN_POINT(48, 27), \
 	FAN_POINT(52, 27), \

src/board/system76/gaze17-3050/board.mk

@@ -39,14 +39,13 @@ CFLAGS+=\
 	-DPOWER_LIMIT_AC=180 \
 	-DPOWER_LIMIT_DC=45
 
-CFLAGS+=-DSMOOTH_FANS_MIN=20
-
 # Enable dGPU support
 CONFIG_HAVE_DGPU = y
 CFLAGS += -DI2C_DGPU=I2C_1
 
 # Fan configs
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=20
 CFLAGS += -DBOARD_FAN1_HEATUP=5
 CFLAGS += -DBOARD_FAN1_COOLDOWN=20
 CFLAGS += -DBOARD_FAN1_POINTS="\
@@ -60,6 +59,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR4
+CFLAGS += -DFAN2_PWM_MIN=20
 CFLAGS += -DBOARD_FAN2_HEATUP=5
 CFLAGS += -DBOARD_FAN2_COOLDOWN=20
 CFLAGS += -DBOARD_FAN2_POINTS="\

src/board/system76/oryp11/board.mk

@@ -49,14 +49,13 @@ CFLAGS+=\
 	-DPOWER_LIMIT_AC=230 \
 	-DPOWER_LIMIT_DC=55
 
-CFLAGS+=-DSMOOTH_FANS_MIN=28
-
 # Enable dGPU support
 CONFIG_HAVE_DGPU = y
 CFLAGS += -DI2C_DGPU=I2C_1
 
 # Fan configs
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=28
 CFLAGS += -DBOARD_FAN1_HEATUP=5
 CFLAGS += -DBOARD_FAN1_COOLDOWN=20
 CFLAGS += -DBOARD_FAN1_POINTS="\
@@ -70,6 +69,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR4
+CFLAGS += -DFAN2_PWM_MIN=28
 CFLAGS += -DBOARD_FAN2_HEATUP=5
 CFLAGS += -DBOARD_FAN2_COOLDOWN=20
 CFLAGS += -DBOARD_FAN2_POINTS="\

src/board/system76/oryp6/board.mk

@@ -33,15 +33,13 @@ CFLAGS+=\
 	-DPOWER_LIMIT_AC=180 \
 	-DPOWER_LIMIT_DC=45
 
-# Don't smooth fan speed changes below 25% to mitigate buzzing
-CFLAGS+=-DSMOOTH_FANS_MIN=25
-
 # Enable dGPU support
 CONFIG_HAVE_DGPU = y
 CFLAGS += -DI2C_DGPU=I2C_1
 
 # Fan configs
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=25
 CFLAGS += -DBOARD_FAN1_POINTS="\
 	FAN_POINT(55, 25), \
 	FAN_POINT(65, 30), \
@@ -53,6 +51,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR4
+CFLAGS += -DFAN2_PWM_MIN=25
 CFLAGS += -DBOARD_FAN2_POINTS="\
 	FAN_POINT(55, 25), \
 	FAN_POINT(65, 30), \

src/board/system76/oryp7/board.mk

@@ -33,15 +33,13 @@ CFLAGS+=\
 	-DPOWER_LIMIT_AC=180 \
 	-DPOWER_LIMIT_DC=45
 
-# Don't smooth fan speed changes below 25% to mitigate buzzing
-CFLAGS+=-DSMOOTH_FANS_MIN=25
-
 # Enable dGPU support
 CONFIG_HAVE_DGPU = y
 CFLAGS += -DI2C_DGPU=I2C_1
 
 # Fan configs
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=25
 CFLAGS += -DBOARD_FAN1_POINTS="\
 	FAN_POINT(55, 25), \
 	FAN_POINT(65, 30), \
@@ -53,6 +51,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR4
+CFLAGS += -DFAN2_PWM_MIN=25
 CFLAGS += -DBOARD_FAN2_POINTS="\
 	FAN_POINT(55, 25), \
 	FAN_POINT(65, 30), \

src/board/system76/oryp8/board.mk

@@ -36,15 +36,13 @@ CFLAGS+=\
 	-DPOWER_LIMIT_AC=180 \
 	-DPOWER_LIMIT_DC=45
 
-# Don't smooth fan speed changes below 25% to mitigate buzzing
-CFLAGS+=-DSMOOTH_FANS_MIN=25
-
 # Enable dGPU support
 CONFIG_HAVE_DGPU = y
 CFLAGS += -DI2C_DGPU=I2C_1
 
 # Fan configs
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=25
 CFLAGS += -DBOARD_FAN1_POINTS="\
 	FAN_POINT(55, 25), \
 	FAN_POINT(65, 30), \
@@ -56,6 +54,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR4
+CFLAGS += -DFAN2_PWM_MIN=25
 CFLAGS += -DBOARD_FAN2_POINTS="\
 	FAN_POINT(55, 25), \
 	FAN_POINT(65, 30), \

src/board/system76/serw13/board.mk

@@ -46,14 +46,13 @@ CFLAGS+=\
 	-DPOWER_LIMIT_AC=280 \
 	-DPOWER_LIMIT_DC=55
 
-CFLAGS+=-DSMOOTH_FANS_MIN=28
-
 # Enable dGPU support
 CONFIG_HAVE_DGPU = y
 CFLAGS += -DI2C_DGPU=I2C_1
 
 # Fan configs
 CFLAGS += -DFAN1_PWM=DCR2
+CFLAGS += -DFAN1_PWM_MIN=28
 CFLAGS += -DBOARD_FAN1_HEATUP=5
 CFLAGS += -DBOARD_FAN1_COOLDOWN=20
 CFLAGS += -DBOARD_FAN1_POINTS="\
@@ -66,6 +65,7 @@ CFLAGS += -DBOARD_FAN1_POINTS="\
 "
 
 CFLAGS += -DFAN2_PWM=DCR4
+CFLAGS += -DFAN2_PWM_MIN=28
 CFLAGS += -DBOARD_FAN2_HEATUP=5
 CFLAGS += -DBOARD_FAN2_COOLDOWN=20
 CFLAGS += -DBOARD_FAN2_POINTS="\