lotus: add slow response fan solution (#864)

* lotus: add slow response fan solution

Signed-off-by: LeoCX_Tsai <[email protected]>

* lotus: use fan.dtsi rpm_deviation

remove margin rpm deviation, use fan node rpm_deviation

Signed-off-by: LeoCX_Tsai <[email protected]>

---------

Signed-off-by: LeoCX_Tsai <[email protected]>

Author: LeoCX-Tsai

zephyr/program/lotus/lotus/project.conf

@@ -12,6 +12,7 @@ CONFIG_PLATFORM_EC_GPU_POWER_CONTROL=y
 
 # Fan
 CONFIG_PLATFORM_EC_NUM_FANS=2
+CONFIG_PLATFORM_EC_FAN_BYPASS_SLOW_RESPONSE=y
 
 #TypeC support
 CONFIG_PLATFORM_EC_USBC=n

zephyr/shim/include/config_chip.h

@@ -739,7 +739,7 @@ extern char mock_jump_data[CONFIG_PLATFORM_EC_PRESERVED_END_OF_RAM_SIZE];
 #endif
 
 #undef CONFIG_FAN_BYPASS_SLOW_RESPONSE
-#ifdef PLATFORM_EC_FAN_BYPASS_SLOW_RESPONSE
+#ifdef CONFIG_PLATFORM_EC_FAN_BYPASS_SLOW_RESPONSE
 #define CONFIG_FAN_BYPASS_SLOW_RESPONSE
 #endif
 

zephyr/shim/src/fan.c

@@ -202,8 +202,19 @@ enum fan_status fan_smart_control(int ch)
 	/* Record previous rpm */
 	data->rpm_pre = rpm_actual;
 
-	/* Adjust PWM duty */
-	rpm_diff = rpm_target - rpm_actual;
+	/*
+	 * A specific type of fan needs a longer time to output the TACH
+	 * signal to EC after EC outputs the PWM signal to the fan.
+	 * During this period, the driver will read two consecutive RPM = 0.
+	 * In this case, don't step the PWM duty too aggressively.
+	 */
+	if (data->rpm_pre == 0 && rpm_actual == 0 &&
+	    IS_ENABLED(CONFIG_PLATFORM_EC_FAN_BYPASS_SLOW_RESPONSE)) {
+		rpm_diff = (rpm_target * deviation / 100) + 1;
+	} else {
+		rpm_diff = rpm_target - rpm_actual;
+	}
+
 	duty = fan_get_duty(ch);
 	if (duty == 0 && rpm_target == 0) {
 		return FAN_STATUS_STOPPED;