[PATCH] platform/chrome: cros_ec: trigger kernel_restart on EC_HOST_EVENT_PANIC

[PATCH] platform/chrome: cros_ec: trigger kernel_restart on EC_HOST_EVENT_PANIC

[Scott Collyer]

When an attached EC or ISH device reports an EC_HOST_EVENT_PANIC host
event, the EC/ISH subsystem has encountered a fatal exception.

Handle the EC_HOST_EVENT_PANIC event by:
1. Logging an emergency message (dev_emerg) with the device name.
2. Calling the panic notifier chain (panic_notifier).
3. Emitting a uevent (ERROR=PANIC) to userspace.
4. Triggering kernel_restart("CrOS EC Panic") to cleanly restart the AP
   so that panic logs are preserved and collected by crash reporting
   services across reboot.

Signed-off-by: Scott Collyer <scollyer@google.com>
---
 drivers/platform/chrome/cros_ec.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
index 1da79e3d215b..cee7018a2d7d 100644
--- a/drivers/platform/chrome/cros_ec.c
+++ b/drivers/platform/chrome/cros_ec.c
@@ -11,11 +11,13 @@
 
 #include <linux/cleanup.h>
 #include <linux/interrupt.h>
+#include <linux/kobject.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/platform_data/cros_ec_commands.h>
 #include <linux/platform_data/cros_ec_proto.h>
+#include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
 
@@ -109,8 +111,10 @@ static irqreturn_t cros_ec_irq_handler(int irq, void *data)
  */
 static bool cros_ec_handle_event(struct cros_ec_device *ec_dev)
 {
+	static const char * const panic_env[] = { "ERROR=PANIC", NULL };
 	bool wake_event;
 	bool ec_has_more_events;
+	u32 host_event;
 	int ret;
 
 	ret = cros_ec_get_next_event(ec_dev, &wake_event, &ec_has_more_events);
@@ -123,9 +127,21 @@ static bool cros_ec_handle_event(struct cros_ec_device *ec_dev)
 	if (wake_event && device_may_wakeup(ec_dev->dev))
 		pm_wakeup_event(ec_dev->dev, 0);
 
-	if (ret > 0)
+	if (ret > 0) {
+		if (ec_dev->event_data.event_type == EC_MKBP_EVENT_HOST_EVENT) {
+			host_event = cros_ec_get_host_event(ec_dev);
+			if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_PANIC)) {
+				dev_emerg(ec_dev->dev, "CrOS EC Panic Reported (%s). Reboot is imminent!\n",
+					  dev_name(ec_dev->dev));
+				blocking_notifier_call_chain(&ec_dev->panic_notifier, 0, ec_dev);
+				kobject_uevent_env(&ec_dev->dev->kobj, KOBJ_CHANGE,
+						   (char **)panic_env);
+				kernel_restart("CrOS EC Panic");
+			}
+		}
 		blocking_notifier_call_chain(&ec_dev->event_notifier,
 					     0, ec_dev);
+	}
 
 	return ec_has_more_events;
 }
-- 
2.56.0.385.gd3acb90ef8-goog

Re: [PATCH] platform/chrome: cros_ec: trigger kernel_restart on EC_HOST_EVENT_PANIC

[Tzung-Bi Shih]

On Thu, Oct 08, 2026 at 10:22:08AM -0700, Scott Collyer wrote:
> When an attached EC or ISH device reports an EC_HOST_EVENT_PANIC host
> event, the EC/ISH subsystem has encountered a fatal exception.
> 
> Handle the EC_HOST_EVENT_PANIC event by:
> 1. Logging an emergency message (dev_emerg) with the device name.
> 2. Calling the panic notifier chain (panic_notifier).
> 3. Emitting a uevent (ERROR=PANIC) to userspace.
> 4. Triggering kernel_restart("CrOS EC Panic") to cleanly restart the AP
>    so that panic logs are preserved and collected by crash reporting
>    services across reboot.

If the EC crashed, wouldn't the AP be reset anyway?

Re: [PATCH] platform/chrome: cros_ec: trigger kernel_restart on EC_HOST_EVENT_PANIC

[Scott Collyer]

When the EC crashes, the AP will be reset as you mentioned. There is a
slight benefit for the EC case with this change in that a controlled
shutdown of the AP gets triggered. But, the primary motivation for
this change is for ISH panic handling. When the ISH resets, there is
currently nothing in place to trigger an AP reboot, and this results
in the sensor stack getting out of sync. So when the ISH panics, we
need the AP to reboot as well.

On Wed, Oct 14, 2026 at 12:17 AM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
>
> On Thu, Oct 08, 2026 at 10:22:08AM -0700, Scott Collyer wrote:
> > When an attached EC or ISH device reports an EC_HOST_EVENT_PANIC host
> > event, the EC/ISH subsystem has encountered a fatal exception.
> >
> > Handle the EC_HOST_EVENT_PANIC event by:
> > 1. Logging an emergency message (dev_emerg) with the device name.
> > 2. Calling the panic notifier chain (panic_notifier).
> > 3. Emitting a uevent (ERROR=PANIC) to userspace.
> > 4. Triggering kernel_restart("CrOS EC Panic") to cleanly restart the AP
> >    so that panic logs are preserved and collected by crash reporting
> >    services across reboot.
>
> If the EC crashed, wouldn't the AP be reset anyway?