[PATCH 2/2] platform/x86: hp-wmi: Expose independent CPU/GPU pwm channels

[foobisdweik <dweikmferris@gmail.com>]

The Victus-S WMI fan-speed-set query (HPWMI_VICTUS_S_FAN_SPEED_SET_QUERY,
GM2E in firmware) takes a two-byte buffer [cpu, gpu] and writes the
values to EC SRP1/SRP2 setpoints independently. The driver however drove
both fans from a single hwmon pwm1 attribute, with the GPU value
derived as cpu + priv->gpu_delta from the fan table. This makes
asymmetric fan curves (common ask: GPU fan louder than CPU under
heavy gaming load) impossible from userspace fan-control tools that
expect one pwm attribute per fan.

Promote priv->pwm to a two-element array, add a second pwm hwmon
channel, and extend hp_wmi_hwmon_write() / hp_wmi_apply_fan_settings()
to drive the per-channel setpoints through GM2E.

The U8_MAX sentinel in hp_wmi_fan_speed_set() selects the new
per-fan path; existing callers using HP_FAN_SPEED_AUTOMATIC or a
direct rpm value keep their behavior. The second pwm channel is only
visible on Victus-S-capable boards, since other HP laptops still use
the legacy single-fan WMI commands.

Tested on OMEN by HP Laptop 16-b1xxx (8A13): writing pwm1=60, pwm2=200
in manual mode drives CPU fan to ~1600 RPM and GPU fan to ~5700 RPM
simultaneously, verified via fan1_input/fan2_input tachs and direct
read of EC offsets 0xB0..0xB3.

Signed-off-by: foobisdweik <dweikmferris@gmail.com>
---
 drivers/platform/x86/hp/hp-wmi.c | 45 +++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index 389506a6d2e3..40eb3715583a 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -486,7 +486,7 @@ struct hp_wmi_hwmon_priv {
 	u8 max_rpm;
 	int gpu_delta;
 	u8 mode;
-	u8 pwm;
+	u8 pwm[2];
 	struct delayed_work keep_alive_dwork;
 };
 
@@ -822,12 +822,18 @@ static int hp_wmi_fan_speed_set(struct hp_wmi_hwmon_priv *priv, u8 speed)
 	fan_speed[GPU_FAN] = speed;
 
 	/*
-	 * GPU fan speed is always a little higher than CPU fan speed, we fetch
-	 * this delta value from the fan table during hwmon init.
-	 * Exception: Speed is set to HP_FAN_SPEED_AUTOMATIC, to revert to
-	 * automatic mode.
+	 * Pass-through value U8_MAX: drive each fan from its own
+	 * priv->pwm[] setpoint converted via pwm_to_rpm(). Used by the
+	 * hwmon pwm1/pwm2 path that allows independent CPU/GPU fan control.
+	 *
+	 * Otherwise: GPU fan speed is always a little higher than CPU fan
+	 * speed; we fetch this delta from the fan table during hwmon init.
+	 * Exception: HP_FAN_SPEED_AUTOMATIC reverts to automatic mode.
 	 */
-	if (speed != HP_FAN_SPEED_AUTOMATIC) {
+	if (speed == U8_MAX) {
+		fan_speed[CPU_FAN] = pwm_to_rpm(priv->pwm[CPU_FAN], priv);
+		fan_speed[GPU_FAN] = pwm_to_rpm(priv->pwm[GPU_FAN], priv);
+	} else if (speed != HP_FAN_SPEED_AUTOMATIC) {
 		gpu_speed = speed + priv->gpu_delta;
 		fan_speed[GPU_FAN] = clamp_val(gpu_speed, 0, U8_MAX);
 	}
@@ -2398,7 +2404,7 @@ static int hp_wmi_apply_fan_settings(struct hp_wmi_hwmon_priv *priv)
 	case PWM_MODE_MANUAL:
 		if (!is_victus_s_thermal_profile())
 			return -EOPNOTSUPP;
-		ret = hp_wmi_fan_speed_set(priv, pwm_to_rpm(priv->pwm, priv));
+		ret = hp_wmi_fan_speed_set(priv, U8_MAX);
 		if (ret < 0)
 			return ret;
 		mod_delayed_work(system_wq, &priv->keep_alive_dwork,
@@ -2429,6 +2435,12 @@ static umode_t hp_wmi_hwmon_is_visible(const void *data,
 {
 	switch (type) {
 	case hwmon_pwm:
+		/*
+		 * Second pwm channel only exists on Victus-S-style boards
+		 * which expose an independent GPU fan setpoint.
+		 */
+		if (channel == 1 && !is_victus_s_thermal_profile())
+			return 0;
 		if (attr == hwmon_pwm_input && !is_victus_s_thermal_profile())
 			return 0;
 		return 0644;
@@ -2514,7 +2526,7 @@ static int hp_wmi_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
 			/* ensure PWM input is within valid fan speeds */
 			rpm = pwm_to_rpm(val, priv);
 			rpm = clamp_val(rpm, priv->min_rpm, priv->max_rpm);
-			priv->pwm = rpm_to_pwm(rpm, priv);
+			priv->pwm[channel] = rpm_to_pwm(rpm, priv);
 			return hp_wmi_apply_fan_settings(priv);
 		}
 		switch (val) {
@@ -2525,13 +2537,18 @@ static int hp_wmi_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
 			if (!is_victus_s_thermal_profile())
 				return -EOPNOTSUPP;
 			/*
-			 * When switching to manual mode, set fan speed to
-			 * current RPM values to ensure a smooth transition.
+			 * When switching to manual mode, seed each per-fan
+			 * setpoint from its current measured RPM so the
+			 * transition is smooth.
 			 */
-			rpm = hp_wmi_get_fan_speed_victus_s(channel);
+			rpm = hp_wmi_get_fan_speed_victus_s(CPU_FAN);
+			if (rpm < 0)
+				return rpm;
+			priv->pwm[CPU_FAN] = rpm_to_pwm(rpm / 100, priv);
+			rpm = hp_wmi_get_fan_speed_victus_s(GPU_FAN);
 			if (rpm < 0)
 				return rpm;
-			priv->pwm = rpm_to_pwm(rpm / 100, priv);
+			priv->pwm[GPU_FAN] = rpm_to_pwm(rpm / 100, priv);
 			priv->mode = PWM_MODE_MANUAL;
 			return hp_wmi_apply_fan_settings(priv);
 		case PWM_MODE_AUTO:
@@ -2547,7 +2564,9 @@ static int hp_wmi_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
 
 static const struct hwmon_channel_info * const info[] = {
 	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT, HWMON_F_INPUT),
-	HWMON_CHANNEL_INFO(pwm, HWMON_PWM_ENABLE | HWMON_PWM_INPUT),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_ENABLE | HWMON_PWM_INPUT,
+			   HWMON_PWM_ENABLE | HWMON_PWM_INPUT),
 	NULL
 };
 
-- 
2.54.0