drivers/acpi/button.c | 13 ++++++++++++- drivers/acpi/sleep.c | 41 ----------------------------------------- 2 files changed, 12 insertions(+), 42 deletions(-)
The ACPI button driver reports KEY_WAKEUP from the Power Button input
device to let userspace know that the system was resumed by a power
button wakeup.
However, reporting KEY_WAKEUP from generic system resume paths can make
userspace observe a Power Button wakeup even when the system was resumed
by a different wake source.
This is reproducible on an AMD Android 15 Xen guest. With a kernel
without this fix, a non-power-button S3 resume:
echo mem > /sys/power/state
xl trigger android s3resume
makes the Power Button input device report KEY_WAKEUP. The same test on
a kernel with this fix no longer reports KEY_WAKEUP from the Power Button
input device.
Track whether a power button event/notify is observed while the ACPI
button device is suspended, and report KEY_WAKEUP on resume only in that
case. Do not synthesize a Power Button input event from generic ACPI
sleep resume code.
Signed-off-by: Baorui.Liu <baorliu@amd.com>
---
drivers/acpi/button.c | 13 ++++++++++++-
drivers/acpi/sleep.c | 41 -----------------------------------------
2 files changed, 12 insertions(+), 42 deletions(-)
diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index cdbb1023a8ee..7a708fe351fb 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -191,6 +191,7 @@ struct acpi_button {
bool last_state;
ktime_t last_time;
bool suspended;
+ bool wakeup_pending;
bool lid_state_initialized;
bool gpe_enabled;
};
@@ -476,6 +477,9 @@ static void acpi_button_notify(acpi_handle handle, u32 event, void *data)
acpi_pm_wakeup_event(button->dev);
+ if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+ button->wakeup_pending = true;
+
if (button->suspended || event == ACPI_BUTTON_NOTIFY_WAKE)
return;
@@ -498,6 +502,11 @@ static void acpi_button_notify_run(void *data)
static u32 acpi_button_event(void *data)
{
+ struct acpi_button *button = data;
+
+ if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+ button->wakeup_pending = true;
+
acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_button_notify_run, data);
return ACPI_INTERRUPT_HANDLED;
}
@@ -508,6 +517,7 @@ static int acpi_button_suspend(struct device *dev)
struct acpi_button *button = dev_get_drvdata(dev);
button->suspended = true;
+ button->wakeup_pending = false;
return 0;
}
@@ -523,12 +533,13 @@ static int acpi_button_resume(struct device *dev)
acpi_lid_initialize_state(button);
}
- if (button->type == ACPI_BUTTON_TYPE_POWER) {
+ if (button->type == ACPI_BUTTON_TYPE_POWER && button->wakeup_pending) {
input = button->input;
input_report_key(input, KEY_WAKEUP, 1);
input_sync(input);
input_report_key(input, KEY_WAKEUP, 0);
input_sync(input);
+ button->wakeup_pending = false;
}
return 0;
}
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 132a9df98471..7296e4bb0e4d 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -104,8 +104,6 @@ u32 acpi_target_system_state(void)
}
EXPORT_SYMBOL_GPL(acpi_target_system_state);
-static bool pwr_btn_event_pending;
-
/*
* The ACPI specification wants us to save NVS memory regions during hibernation
* and to restore them during the subsequent resume. Windows does that also for
@@ -484,7 +482,6 @@ static int acpi_pm_prepare(void)
*/
static void acpi_pm_finish(void)
{
- struct acpi_device *pwr_btn_adev;
u32 acpi_state = acpi_target_sleep_state;
acpi_ec_unblock_transactions();
@@ -503,23 +500,6 @@ static void acpi_pm_finish(void)
acpi_target_sleep_state = ACPI_STATE_S0;
acpi_resume_power_resources();
-
- /* If we were woken with the fixed power button, provide a small
- * hint to userspace in the form of a wakeup event on the fixed power
- * button device (if it can be found).
- *
- * We delay the event generation til now, as the PM layer requires
- * timekeeping to be running before we generate events. */
- if (!pwr_btn_event_pending)
- return;
-
- pwr_btn_event_pending = false;
- pwr_btn_adev = acpi_dev_get_first_match_dev(ACPI_BUTTON_HID_POWERF,
- NULL, -1);
- if (pwr_btn_adev) {
- pm_wakeup_event(&pwr_btn_adev->dev, 0);
- acpi_dev_put(pwr_btn_adev);
- }
}
/**
@@ -626,27 +606,6 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
/* Reprogram control registers */
acpi_leave_sleep_state_prep(acpi_state);
- /* ACPI 3.0 specs (P62) says that it's the responsibility
- * of the OSPM to clear the status bit [ implying that the
- * POWER_BUTTON event should not reach userspace ]
- *
- * However, we do generate a small hint for userspace in the form of
- * a wakeup event. We flag this condition for now and generate the
- * event later, as we're currently too early in resume to be able to
- * generate wakeup events.
- */
- if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3)) {
- acpi_event_status pwr_btn_status = ACPI_EVENT_FLAG_DISABLED;
-
- acpi_get_event_status(ACPI_EVENT_POWER_BUTTON, &pwr_btn_status);
-
- if (pwr_btn_status & ACPI_EVENT_FLAG_STATUS_SET) {
- acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
- /* Flag for later */
- pwr_btn_event_pending = true;
- }
- }
-
/*
* Disable all GPE and clear their status bits before interrupts are
* enabled. Some GPEs (like wakeup GPEs) have no handlers and this can
--
2.34.1On Thu, Sep 17, 2026 at 4:31 PM Baorui.Liu <baorliu@amd.com> wrote:
>
> The ACPI button driver reports KEY_WAKEUP from the Power Button input
> device to let userspace know that the system was resumed by a power
> button wakeup.
>
> However, reporting KEY_WAKEUP from generic system resume paths can make
> userspace observe a Power Button wakeup even when the system was resumed
> by a different wake source.
>
> This is reproducible on an AMD Android 15 Xen guest. With a kernel
> without this fix, a non-power-button S3 resume:
>
> echo mem > /sys/power/state
> xl trigger android s3resume
>
> makes the Power Button input device report KEY_WAKEUP. The same test on
> a kernel with this fix no longer reports KEY_WAKEUP from the Power Button
> input device.
>
> Track whether a power button event/notify is observed while the ACPI
> button device is suspended, and report KEY_WAKEUP on resume only in that
> case. Do not synthesize a Power Button input event from generic ACPI
> sleep resume code.
>
> Signed-off-by: Baorui.Liu <baorliu@amd.com>
Please see
https://sashiko.dev/#/patchset/20260917143116.445-1-baorliu%40amd.com
and tell me what you think.
Thanks!
> ---
> drivers/acpi/button.c | 13 ++++++++++++-
> drivers/acpi/sleep.c | 41 -----------------------------------------
> 2 files changed, 12 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index cdbb1023a8ee..7a708fe351fb 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -191,6 +191,7 @@ struct acpi_button {
> bool last_state;
> ktime_t last_time;
> bool suspended;
> + bool wakeup_pending;
> bool lid_state_initialized;
> bool gpe_enabled;
> };
> @@ -476,6 +477,9 @@ static void acpi_button_notify(acpi_handle handle, u32 event, void *data)
>
> acpi_pm_wakeup_event(button->dev);
>
> + if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
> + button->wakeup_pending = true;
> +
> if (button->suspended || event == ACPI_BUTTON_NOTIFY_WAKE)
> return;
>
> @@ -498,6 +502,11 @@ static void acpi_button_notify_run(void *data)
>
> static u32 acpi_button_event(void *data)
> {
> + struct acpi_button *button = data;
> +
> + if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
> + button->wakeup_pending = true;
> +
> acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_button_notify_run, data);
> return ACPI_INTERRUPT_HANDLED;
> }
> @@ -508,6 +517,7 @@ static int acpi_button_suspend(struct device *dev)
> struct acpi_button *button = dev_get_drvdata(dev);
>
> button->suspended = true;
> + button->wakeup_pending = false;
> return 0;
> }
>
> @@ -523,12 +533,13 @@ static int acpi_button_resume(struct device *dev)
> acpi_lid_initialize_state(button);
> }
>
> - if (button->type == ACPI_BUTTON_TYPE_POWER) {
> + if (button->type == ACPI_BUTTON_TYPE_POWER && button->wakeup_pending) {
> input = button->input;
> input_report_key(input, KEY_WAKEUP, 1);
> input_sync(input);
> input_report_key(input, KEY_WAKEUP, 0);
> input_sync(input);
> + button->wakeup_pending = false;
> }
> return 0;
> }
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index 132a9df98471..7296e4bb0e4d 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -104,8 +104,6 @@ u32 acpi_target_system_state(void)
> }
> EXPORT_SYMBOL_GPL(acpi_target_system_state);
>
> -static bool pwr_btn_event_pending;
> -
> /*
> * The ACPI specification wants us to save NVS memory regions during hibernation
> * and to restore them during the subsequent resume. Windows does that also for
> @@ -484,7 +482,6 @@ static int acpi_pm_prepare(void)
> */
> static void acpi_pm_finish(void)
> {
> - struct acpi_device *pwr_btn_adev;
> u32 acpi_state = acpi_target_sleep_state;
>
> acpi_ec_unblock_transactions();
> @@ -503,23 +500,6 @@ static void acpi_pm_finish(void)
> acpi_target_sleep_state = ACPI_STATE_S0;
>
> acpi_resume_power_resources();
> -
> - /* If we were woken with the fixed power button, provide a small
> - * hint to userspace in the form of a wakeup event on the fixed power
> - * button device (if it can be found).
> - *
> - * We delay the event generation til now, as the PM layer requires
> - * timekeeping to be running before we generate events. */
> - if (!pwr_btn_event_pending)
> - return;
> -
> - pwr_btn_event_pending = false;
> - pwr_btn_adev = acpi_dev_get_first_match_dev(ACPI_BUTTON_HID_POWERF,
> - NULL, -1);
> - if (pwr_btn_adev) {
> - pm_wakeup_event(&pwr_btn_adev->dev, 0);
> - acpi_dev_put(pwr_btn_adev);
> - }
> }
>
> /**
> @@ -626,27 +606,6 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
> /* Reprogram control registers */
> acpi_leave_sleep_state_prep(acpi_state);
>
> - /* ACPI 3.0 specs (P62) says that it's the responsibility
> - * of the OSPM to clear the status bit [ implying that the
> - * POWER_BUTTON event should not reach userspace ]
> - *
> - * However, we do generate a small hint for userspace in the form of
> - * a wakeup event. We flag this condition for now and generate the
> - * event later, as we're currently too early in resume to be able to
> - * generate wakeup events.
> - */
> - if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3)) {
> - acpi_event_status pwr_btn_status = ACPI_EVENT_FLAG_DISABLED;
> -
> - acpi_get_event_status(ACPI_EVENT_POWER_BUTTON, &pwr_btn_status);
> -
> - if (pwr_btn_status & ACPI_EVENT_FLAG_STATUS_SET) {
> - acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
> - /* Flag for later */
> - pwr_btn_event_pending = true;
> - }
> - }
> -
> /*
> * Disable all GPE and clear their status bits before interrupts are
> * enabled. Some GPEs (like wakeup GPEs) have no handlers and this can
> --
> 2.34.1
>
The ACPI button driver reports KEY_WAKEUP from the Power Button input
device to let userspace know that the system was resumed by a power
button wakeup.
However, reporting KEY_WAKEUP from generic system resume paths can make
userspace observe a Power Button wakeup even when the system was resumed
by a different wake source.
This is reproducible on an AMD Android 15 Xen guest. With a kernel
without this fix, a non-power-button S3 resume:
echo mem > /sys/power/state
xl trigger android s3resume
makes the Power Button input device report KEY_WAKEUP. The same test on
a kernel with this fix no longer reports KEY_WAKEUP from the Power Button
input device.
Track whether a power button event/notify is observed while the ACPI
button device is suspended, and report KEY_WAKEUP on resume only in that
case.
When the fixed power-button status bit is set during early S3 resume,
clear it to avoid a deferred KEY_POWER delivery to userspace, and mark
wakeup_pending so button resume can still report KEY_WAKEUP. Also clear
wakeup_pending before setting suspended to avoid a race with a power
button SCI during suspend entry.
Signed-off-by: Baorui.Liu <baorliu@amd.com>
---
drivers/acpi/button.c | 46 ++++++++++++++++++++++++++++++++++++++++++-
drivers/acpi/sleep.c | 27 +++++++++++--------------
include/acpi/button.h | 5 +++++
3 files changed, 62 insertions(+), 16 deletions(-)
diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index cdbb1023a8ee..c07de417df5d 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -191,6 +191,7 @@ struct acpi_button {
bool last_state;
ktime_t last_time;
bool suspended;
+ bool wakeup_pending;
bool lid_state_initialized;
bool gpe_enabled;
};
@@ -397,6 +398,34 @@ static void acpi_lid_forget(struct acpi_device *adev)
}
/* Driver Interface */
+/**
+ * acpi_button_power_wakeup_pending - Mark fixed power button wakeup pending.
+ *
+ * Used when the fixed power-button status bit is observed and cleared during
+ * early S3 resume, so KEY_WAKEUP can still be reported from button resume
+ * without delivering a deferred KEY_POWER to userspace.
+ */
+void acpi_button_power_wakeup_pending(void)
+{
+ struct acpi_device *adev;
+ struct device *phys_dev;
+ struct acpi_button *button;
+
+ adev = acpi_dev_get_first_match_dev(ACPI_BUTTON_HID_POWERF, NULL, -1);
+ if (!adev)
+ return;
+
+ phys_dev = acpi_get_first_physical_node(adev);
+ if (phys_dev) {
+ button = dev_get_drvdata(phys_dev);
+ if (button && button->type == ACPI_BUTTON_TYPE_POWER)
+ button->wakeup_pending = true;
+ }
+
+ acpi_dev_put(adev);
+}
+EXPORT_SYMBOL_GPL(acpi_button_power_wakeup_pending);
+
int acpi_lid_open(void)
{
guard(mutex)(&acpi_lid_lock);
@@ -476,6 +505,9 @@ static void acpi_button_notify(acpi_handle handle, u32 event, void *data)
acpi_pm_wakeup_event(button->dev);
+ if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+ button->wakeup_pending = true;
+
if (button->suspended || event == ACPI_BUTTON_NOTIFY_WAKE)
return;
@@ -498,6 +530,11 @@ static void acpi_button_notify_run(void *data)
static u32 acpi_button_event(void *data)
{
+ struct acpi_button *button = data;
+
+ if (button->type == ACPI_BUTTON_TYPE_POWER && button->suspended)
+ button->wakeup_pending = true;
+
acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_button_notify_run, data);
return ACPI_INTERRUPT_HANDLED;
}
@@ -507,6 +544,12 @@ static int acpi_button_suspend(struct device *dev)
{
struct acpi_button *button = dev_get_drvdata(dev);
+ /*
+ * Clear wakeup_pending before marking suspended. Otherwise a power
+ * button SCI between the two stores could set wakeup_pending and then
+ * be overwritten here, losing a real wakeup.
+ */
+ button->wakeup_pending = false;
button->suspended = true;
return 0;
}
@@ -523,12 +566,13 @@ static int acpi_button_resume(struct device *dev)
acpi_lid_initialize_state(button);
}
- if (button->type == ACPI_BUTTON_TYPE_POWER) {
+ if (button->type == ACPI_BUTTON_TYPE_POWER && button->wakeup_pending) {
input = button->input;
input_report_key(input, KEY_WAKEUP, 1);
input_sync(input);
input_report_key(input, KEY_WAKEUP, 0);
input_sync(input);
+ button->wakeup_pending = false;
}
return 0;
}
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 132a9df98471..30e268987e37 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -22,6 +22,7 @@
#include <linux/syscore_ops.h>
#include <asm/io.h>
#include <trace/events/power.h>
+#include <acpi/button.h>
#include "internal.h"
#include "sleep.h"
@@ -504,12 +505,11 @@ static void acpi_pm_finish(void)
acpi_resume_power_resources();
- /* If we were woken with the fixed power button, provide a small
- * hint to userspace in the form of a wakeup event on the fixed power
- * button device (if it can be found).
- *
- * We delay the event generation til now, as the PM layer requires
- * timekeeping to be running before we generate events. */
+ /*
+ * If woken by the fixed power button, provide a wakeup event on that
+ * device. KEY_WAKEUP input reporting is handled by the button driver
+ * via wakeup_pending; do not synthesize KEY_POWER here.
+ */
if (!pwr_btn_event_pending)
return;
@@ -626,14 +626,11 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
/* Reprogram control registers */
acpi_leave_sleep_state_prep(acpi_state);
- /* ACPI 3.0 specs (P62) says that it's the responsibility
- * of the OSPM to clear the status bit [ implying that the
- * POWER_BUTTON event should not reach userspace ]
- *
- * However, we do generate a small hint for userspace in the form of
- * a wakeup event. We flag this condition for now and generate the
- * event later, as we're currently too early in resume to be able to
- * generate wakeup events.
+ /*
+ * ACPI 3.0 (P62): OSPM should clear the fixed power-button status bit
+ * so the event does not reach userspace as KEY_POWER. Remember that a
+ * power-button wake occurred so button resume can report KEY_WAKEUP
+ * and acpi_pm_finish() can emit a PM wakeup event.
*/
if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3)) {
acpi_event_status pwr_btn_status = ACPI_EVENT_FLAG_DISABLED;
@@ -642,8 +639,8 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
if (pwr_btn_status & ACPI_EVENT_FLAG_STATUS_SET) {
acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
- /* Flag for later */
pwr_btn_event_pending = true;
+ acpi_button_power_wakeup_pending();
}
}
diff --git a/include/acpi/button.h b/include/acpi/button.h
index af2fce5d2ee3..213c6cfd0264 100644
--- a/include/acpi/button.h
+++ b/include/acpi/button.h
@@ -8,11 +8,16 @@
#if IS_ENABLED(CONFIG_ACPI_BUTTON)
extern int acpi_lid_open(void);
+extern void acpi_button_power_wakeup_pending(void);
#else
static inline int acpi_lid_open(void)
{
return 1;
}
+
+static inline void acpi_button_power_wakeup_pending(void)
+{
+}
#endif /* IS_ENABLED(CONFIG_ACPI_BUTTON) */
#endif /* ACPI_BUTTON_H */
--
2.34.1© 2016 - 2026 Red Hat, Inc.