Re: [PATCH 1/2] usb: gadget: u_ether: Do not make UDC parent of the net device

From: Alan Stern
Date: Thu Feb 09 2023 - 10:05:40 EST


On Thu, Feb 09, 2023 at 12:41:03PM +0100, Sascha Hauer wrote:
> I just checked on the host side: With or without my patch I get
> NO-CARRIER on the host. I have to do a 'ip link set usb0 up' on
> the device side, with that I get a <BROADCAST,MULTICAST,UP,LOWER_UP>
> on the host side.
>
> Could it be that my patch breaks something on the device side that
> prevents the device from bringing the link up?

Sascha:

When you first posted your original patch, I wondered if it was really
the right thing to do. Making the net device not be a child of the UDC
device means you can (in theory) have strange behavior such as the
kernel suspending the USB device controller while expecting the network
interface to keep on working.

Is there a different way of solving the original problem?

Alan Stern