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Date: Fri, 17 Jul 2026 12:37:32 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Akshay Gujar <Akshay.Gujar@harman.com>
Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	naveen.v@harman.com, oneukum@suse.com, stern@rowland.harvard.edu
Subject: Re: [PATCH v5 2/3] Documentation: ABI: document
 DEVICE_ENUMERATION_FAILURE uevent
Message-ID: <2026071745-ambulance-reload-4e29@gregkh>
References: <20260715114028.3627807-1-Akshay.Gujar@harman.com>
 <20260715114028.3627807-3-Akshay.Gujar@harman.com>
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In-Reply-To: <20260715114028.3627807-3-Akshay.Gujar@harman.com>

On Wed, Jul 15, 2026 at 11:40:27AM +0000, Akshay Gujar wrote:
> Document the DEVICE_ENUMERATION_FAILURE environment variable emitted
> in KOBJ_CHANGE uevents when device enumeration fails.
> 
> Signed-off-by: Akshay Gujar <Akshay.Gujar@harman.com>
> ---
>  Documentation/ABI/testing/sysfs-uevent | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-uevent b/Documentation/ABI/testing/sysfs-uevent
> index 0b6227706b35e..e362c34aa2ef6 100644
> --- a/Documentation/ABI/testing/sysfs-uevent
> +++ b/Documentation/ABI/testing/sysfs-uevent
> @@ -49,3 +49,28 @@ Description:
>  
>  Users:
>                  udev, userspace tools generating synthetic uevents
> +
> +What:          DEVICE_ENUMERATION_FAILURE
> +Date:          July 2026
> +KernelVersion: 7.3
> +Description:
> +               Some devices may be detected but fail to enumerate
> +               due to protocol-level errors or invalid responses.
> +
> +               A KOBJ_CHANGE uevent includes the following environment
> +               variable when this occurs:
> +
> +                 DEVICE_ENUMERATION_FAILURE=<dev_name>
> +
> +               The value is the kernel device name of the device for
> +               which enumeration failed, as returned by dev_name().
> +
> +               Example (USB):
> +
> +               ACTION=change
> +               SUBSYSTEM=usb
> +               DEVTYPE=usb_interface

This will be the port device, not the usb interface, right?

> +               DEVICE_ENUMERATION_FAILURE=usb1-port1

That looks right.

> +
> +Users:
> +               udev, userspace tools monitoring device enumeration failures
> \ No newline at end of file

Didn't checkpatch complain about this?

And is there actually udev code to handle this being proposed anywhere?

thanks,

greg k-h