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Subject: Re: [RFC RESEND PATCH 0/1] USB EHCI: repeated resets on full and low
 speed devices
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     gregkh@linuxfoundation.org, erkka.talvitie@vincit.fi,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
References: <cover.1598887346.git.khalid@gonehiking.org>
 <20200901023117.GD571008@rowland.harvard.edu>
 <608418fa-b0ce-c2a4-ad79-fe505c842587@oracle.com>
 <20200901163602.GG587030@rowland.harvard.edu>
From:   Khalid Aziz <khalid.aziz@oracle.com>
Organization: Oracle Corp
Message-ID: <4d1ab90a-ec55-85e8-d646-cfa58f08d449@oracle.com>
Date:   Tue, 1 Sep 2020 11:00:16 -0600
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On 9/1/20 10:36 AM, Alan Stern wrote:
> On Tue, Sep 01, 2020 at 09:15:46AM -0700, Khalid Aziz wrote:
>> On 8/31/20 8:31 PM, Alan Stern wrote:
>>> Can you collect a usbmon trace showing an example of this problem?
>>>
>>
>> I have attached usbmon traces for when USB hub with keyboards and mous=
e
>> is plugged into USB 2.0 port and when it is plugged into the NEC USB 3=
=2E0
>> port.
>=20
> The usbmon traces show lots of errors, but no Clear-TT events.  The=20
> large number of errors suggests that you've got a hardware problem;=20
> either a bad hub or bad USB connections.

That is what I thought initially which is why I got additional hubs and
a USB 2.0 PCI card to test. I am seeing errors across 3 USB controllers,
4 USB hubs and 4 slow/full speed devices. All of the hubs and slow/full
devices work with zero errors on my laptop. My keyboard/mouse devices
and 2 of my USB hubs predate motherboard update and they all worked
flawlessly before the motherboard upgrade. Some combinations of these
also works with no errors on my desktop with new motherboard that I had
listed in my original email:

2. USB 2.0 controller - WORKS
5. USB 3.0/3.1 controller -> Bus powered USB 2.0 hub - WORKS

I am not seeing a common failure here that would point to any specific
hardware being bad. Besides, that one code change (which I still can't
say is the right code change) in ehci-q.c makes USB 2.0 controller work
reliably with all my devices.

--
Khalid