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From:   Ondrej Zary <linux@zary.sk>
To:     Jakub Kicinski <kuba@kernel.org>
Subject: Re: [PATCH 1/2] cx82310_eth: re-enable ethernet mode after router reboot
Date:   Mon, 12 Oct 2020 12:42:55 +0200
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Cc:     Oliver Neukum <oneukum@suse.com>, netdev@vger.kernel.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20201010140048.12067-1-linux@zary.sk> <20201011155539.315bf5aa@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
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On Monday 12 October 2020, Jakub Kicinski wrote:
> On Sat, 10 Oct 2020 16:00:46 +0200 Ondrej Zary wrote:
> > When the router is rebooted without a power cycle, the USB device
> > remains connected but its configuration is reset. This results in
> > a non-working ethernet connection with messages like this in syslog:
> > 	usb 2-2: RX packet too long: 65535 B
> >
> > Re-enable ethernet mode when receiving a packet with invalid size of
> > 0xffff.
>
> Patch looks good, but could you explain what's a reboot without a power
> cycle in this case? The modem gets reset but USB subsystem doesn't know
> it and doesn't go though a unbind() + bind() cycle?

The router can be rebooted through the web interface. The reboot does not 
disconnect the USB device - it remains connected as if nothing happened. Only 
wrong data starts to come in.

-- 
Ondrej Zary