[PATCH 2/2] platform/x86: hp-wmi: Add ACPI PWM fan control for HP ENVY 13-bd0xxx
From: Bani Brata
Date: Sun Mar 29 2026 - 01:39:25 EST
On the HP ENVY x360 Convertible 13-bd0xxx (board 8824), standard WMI
methods for fan speed control and RPM reporting do not function.
However, the DSDT exposes ACPI methods (\_SB.PC00.LPCB.EC0.FANG and FANW)
that allow reading and writing an 8-bit PWM level (0-255) to the EC.
This patch maps these ACPI methods to standard hwmon `pwm1` and
`pwm1_enable` nodes, allowing userspace tools to successfully control
the fan speed.
Signed-off-by: Bani Brata <banibrata2007@xxxxxxxxx>
---
drivers/platform/x86/hp/hp-wmi.c | 155 ++++++++++++++++++++++++++++++-
1 file changed, 155 insertions(+)
diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index XXXXXXX..XXXXXXX 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -48,6 +48,14 @@
#define HP_FAN_SPEED_AUTOMATIC 0x00
#define HP_POWER_LIMIT_DEFAULT 0x00
#define HP_POWER_LIMIT_NO_CHANGE 0xFF
+#define HP_ENVY_8824_ACPI_FANG "\\_SB.PC00.LPCB.EC0.FANG"
+#define HP_ENVY_8824_ACPI_FANW "\\_SB.PC00.LPCB.EC0.FANW"
+#define HP_ENVY_8824_FAN_VALUE_ARG 33026ULL
+#define HP_ENVY_8824_FAN_PRIME_ARG 33030ULL
+#define HP_ENVY_8824_FAN_PRIME_MANUAL 0xFFULL
+#define HP_ENVY_8824_FAN_PRIME_AUTO 0x8ULL
+#define HP_ENVY_8824_PWM_MODE_MANUAL 1
+#define HP_ENVY_8824_PWM_MODE_AUTO 2
#define ACPI_AC_CLASS "ac_adapter"
@@ -193,6 +201,8 @@ static const struct dmi_system_id hp_wmi_rfkill_dmi_table[] __initconst = {
static bool is_victus_s_board;
static bool is_envy_x360_8824_board;
+static DEFINE_MUTEX(hp_envy_x360_8824_fan_lock);
+static int hp_envy_x360_8824_pwm_mode = HP_ENVY_8824_PWM_MODE_AUTO;
static const struct dmi_system_id hp_envy_x360_8824_boards[] __initconst = {
{
@@ -518,6 +528,120 @@ static int hp_wmi_get_fan_speed_victus_s(int fan)
return ret;
}
+static int hp_envy_x360_8824_acpi_eval(const char *path,
+ const unsigned long long *args,
+ size_t arg_count,
+ unsigned long long *value)
+{
+ struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+ union acpi_object params[2] = { };
+ struct acpi_object_list input = { .count = arg_count, .pointer = params };
+ union acpi_object *obj;
+ acpi_status status;
+ size_t i;
+
+ for (i = 0; i < arg_count; i++) {
+ params[i].type = ACPI_TYPE_INTEGER;
+ params[i].integer.value = args[i];
+ }
+
+ status = acpi_evaluate_object(NULL, (acpi_string)path,
+ arg_count ? &input : NULL, &output);
+ if (ACPI_FAILURE(status))
+ return -EIO;
+
+ obj = output.pointer;
+ if (!obj)
+ return -ENODATA;
+
+ if (obj->type != ACPI_TYPE_INTEGER) {
+ kfree(obj);
+ return -EINVAL;
+ }
+
+ *value = obj->integer.value;
+ kfree(obj);
+
+ return 0;
+}
+
+static int hp_envy_x360_8824_get_pwm_locked(void)
+{
+ unsigned long long args[] = { HP_ENVY_8824_FAN_VALUE_ARG };
+ unsigned long long value;
+ int ret;
+
+ ret = hp_envy_x360_8824_acpi_eval(HP_ENVY_8824_ACPI_FANG, args,
+ ARRAY_SIZE(args), &value);
+ if (ret)
+ return ret;
+ if (value > U8_MAX)
+ return -EINVAL;
+
+ return value;
+}
+
+static int hp_envy_x360_8824_set_pwm_locked(u8 pwm)
+{
+ unsigned long long args[] = {
+ HP_ENVY_8824_FAN_PRIME_ARG,
+ HP_ENVY_8824_FAN_PRIME_MANUAL,
+ };
+ unsigned long long value;
+ int ret;
+
+ ret = hp_envy_x360_8824_acpi_eval(HP_ENVY_8824_ACPI_FANW, args,
+ ARRAY_SIZE(args), &value);
+ if (ret)
+ return ret;
+
+ args[0] = HP_ENVY_8824_FAN_VALUE_ARG;
+ args[1] = pwm;
+ ret = hp_envy_x360_8824_acpi_eval(HP_ENVY_8824_ACPI_FANW, args,
+ ARRAY_SIZE(args), &value);
+ if (ret)
+ return ret;
+
+ hp_envy_x360_8824_pwm_mode = HP_ENVY_8824_PWM_MODE_MANUAL;
+ return 0;
+}
+
+static int hp_envy_x360_8824_set_auto_locked(void)
+{
+ unsigned long long args[] = {
+ HP_ENVY_8824_FAN_PRIME_ARG,
+ HP_ENVY_8824_FAN_PRIME_AUTO,
+ };
+ unsigned long long value;
+ int ret;
+
+ ret = hp_envy_x360_8824_acpi_eval(HP_ENVY_8824_ACPI_FANW, args,
+ ARRAY_SIZE(args), &value);
+ if (ret)
+ return ret;
+
+ args[0] = HP_ENVY_8824_FAN_VALUE_ARG;
+ args[1] = HP_ENVY_8824_FAN_PRIME_MANUAL;
+ ret = hp_envy_x360_8824_acpi_eval(HP_ENVY_8824_ACPI_FANW, args,
+ ARRAY_SIZE(args), &value);
+ if (ret)
+ return ret;
+
+ hp_envy_x360_8824_pwm_mode = HP_ENVY_8824_PWM_MODE_AUTO;
+ return 0;
+}
+
+static int hp_envy_x360_8824_set_manual_locked(void)
+{
+ int pwm;
+
+ pwm = hp_envy_x360_8824_get_pwm_locked();
+ if (pwm < 0)
+ return pwm;
+
+ return hp_envy_x360_8824_set_pwm_locked(pwm);
+}
+
/*
* Calling this hp_wmi_get_fan_count_userdefine_trigger function also enables
* and/or maintains the laptop in user defined thermal and fan states, instead
@@ -2103,6 +2227,12 @@ static void hp_wmi_rfkill_setup(struct platform_device *device)
rfkill_unregister(wifi_rfkill);
rfkill_destroy(wifi_rfkill);
}
+
+ if (is_envy_x360_8824_board) {
+ mutex_lock(&hp_envy_x360_8824_fan_lock);
+ hp_envy_x360_8824_set_auto_locked();
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ }
if (bluetooth_rfkill) {
rfkill_unregister(bluetooth_rfkill);
rfkill_destroy(bluetooth_rfkill);
@@ -2176,6 +2306,10 @@ static umode_t hp_wmi_hwmon_is_visible(const void *data,
{
switch (type) {
case hwmon_pwm:
+ if (attr == hwmon_pwm_input)
+ return is_envy_x360_8824_board ? 0644 : 0;
+ if (attr == hwmon_pwm_enable)
+ return is_envy_x360_8824_board ? 0644 : 0;
return 0644;
case hwmon_fan:
if (is_envy_x360_8824_board)
@@ -2213,6 +2347,25 @@ static int hp_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
*val = ret;
return 0;
case hwmon_pwm:
+ if (is_envy_x360_8824_board) {
+ mutex_lock(&hp_envy_x360_8824_fan_lock);
+ if (attr == hwmon_pwm_input) {
+ ret = hp_envy_x360_8824_get_pwm_locked();
+ if (!ret)
+ *val = ret;
+ else if (ret > 0)
+ *val = ret;
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return ret < 0 ? ret : 0;
+ }
+ if (attr == hwmon_pwm_enable) {
+ *val = hp_envy_x360_8824_pwm_mode;
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return 0;
+ }
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return -EOPNOTSUPP;
+ }
switch (hp_wmi_fan_speed_max_get()) {
case 0:
/* 0 is automatic fan, which is 2 for hwmon */
@@ -2236,8 +2389,40 @@ static int hp_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
static int hp_wmi_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long val)
{
+ int ret;
+
switch (type) {
case hwmon_pwm:
+ if (is_envy_x360_8824_board) {
+ mutex_lock(&hp_envy_x360_8824_fan_lock);
+ switch (attr) {
+ case hwmon_pwm_input:
+ if (val < 0 || val > U8_MAX) {
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return -EINVAL;
+ }
+ ret = hp_envy_x360_8824_set_pwm_locked(val);
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return ret;
+ case hwmon_pwm_enable:
+ switch (val) {
+ case HP_ENVY_8824_PWM_MODE_MANUAL:
+ ret = hp_envy_x360_8824_set_manual_locked();
+ break;
+ case HP_ENVY_8824_PWM_MODE_AUTO:
+ ret = hp_envy_x360_8824_set_auto_locked();
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return ret;
+ default:
+ mutex_unlock(&hp_envy_x360_8824_fan_lock);
+ return -EOPNOTSUPP;
+ }
+ }
switch (val) {
case 0:
if (is_victus_s_thermal_profile())
@@ -2262,7 +2447,7 @@ 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_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
NULL
};
--
2.48.1