What to do if USB stack seems dead

[Hans Petter Selasky]

On 09/07/14 08:42, Poul-Henning Kamp wrote:
> --------
> In message <540B7AC4.9060504 at selasky.org>, Hans Petter Selasky writes:
>> On 09/06/14 21:57, Maxim V FIlimonov wrote:
>>> Lately, I've been heavily experimenting with different USB devices (for
>>> instance, USB to TTL one, but that's another story), and at a moment I
>>> encountered that the system doesn't react on new USB devices connected. The
>>> connected devices work fine, though. The question is: what can I do in such a
>>> case if I don't want to reboot my box?
>>>
>>
>> Hi,
>>
>> If a TTY port is not closed, it will prevent other USB devices on that
>> particular USB controller from enumerating.
>
> I'm pretty sure I have seen this "dead USB" thing on
>
> 	FreeBSD ni.freebsd.dk 11.0-CURRENT FreeBSD 11.0-CURRENT #3 r270830:
>
> without any USB/TTY ports being involved at all...
>

Hi,

If it is a USB SW problem, you should see that the USB explore / RootHub 
threads are stuck. Else it is a USB HW problem.

--HPS