[PATCH v6 2/3] Documentation: ABI: document DEVICE_ENUMERATION_FAILURE uevent

[Akshay Gujar]

Document the DEVICE_ENUMERATION_FAILURE environment variable emitted
in KOBJ_CHANGE uevents when device enumeration fails.

Signed-off-by: Akshay Gujar <Akshay.Gujar@xxxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-uevent | 37 ++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-uevent b/Documentation/ABI/testing/sysfs-uevent
index 0b6227706b35e..6ace99f99daa3 100644
--- a/Documentation/ABI/testing/sysfs-uevent
+++ b/Documentation/ABI/testing/sysfs-uevent
@@ -49,3 +49,40 @@ Description:
 
 Users:
                 udev, userspace tools generating synthetic uevents
+
+What:           DEVICE_ENUMERATION_FAILURE
+Date:           August 2026
+KernelVersion:  7.3
+Description:
+                Some devices are detected as physically present but fail
+                to enumerate, for example due to protocol-level errors or
+                invalid responses.
+
+                When this happens, a bus driver may emit a KOBJ_CHANGE
+                uevent containing:
+
+                  DEVICE_ENUMERATION_FAILURE=<identifier>
+
+		 The value is a bus-specific identifier of the port or slot
+		 on which enumeration failed, not the name of the device
+		 that emitted the event. For USB this is the port device
+		 name, e.g. "usb1-port1".
+
+                 Example (USB):
+
+                  ACTION=change
+                  SUBSYSTEM=usb
+                  DEVTYPE=usb_interface
+                  DEVPATH=/devices/.../usb1/1-0:1.0
+                  DEVICE_ENUMERATION_FAILURE=usb1-port1
+
+                The event is emitted from the hub interface that owns the
+                port, so DEVPATH refers to the interface. Appending the
+                identifier to DEVPATH gives the failing port:
+
+                  /sys/devices/.../usb1/1-0:1.0/usb1-port1/
+
+Users:
+		udev, userspace tools monitoring device enumeration
+		failures
+
-- 
2.19.0