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From:   Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Date:   Sun, 13 Jan 2019 20:00:38 +0100
Message-ID: <CAJ0CqmU7k5i26g7dGPxNdts7Gm67W6qNsr4vYuW05ugsEF1ohw@mail.gmail.com>
Subject: Re: MT76x2U crashes XHCI driver on AMD Ryzen system
To:     Rosen Penev <rosenp@gmail.com>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>
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>
>
> On Sun, Jan 13, 2019 at 5:33 AM, Lorenzo Bianconi <lorenzo.bianconi@redhat.com> wrote:
>
> Direct. No VM used. This is the only peripheral causing this issue.
>
> Is the device connected to a usb3.0 port? If so, could you please try to connect the dongle to a 2.0 one?
>
> I tried through a USB 2.0 port. Shouldn't make a difference as they both use the xhci driver.
>

mt76x2u supports scatter-gather on usb 3.0 (not on 2.0)

> Could you please double check if IOMMU is enabled?
>

Have you tried to disable it? Does it make any difference?

Regards,
Lorenzo

> It is.
>
> Note that this does not happen on kernel 4.15 (Ubuntu's kernel) as mt76 lacks support.
>
> Regards, Lorenzo
>
>
>