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From:   Rosen Penev <rosenp@gmail.com>
Date:   Sun, 13 Jan 2019 18:20:53 -0800
Message-ID: <CAKxU2N-+CTaRdJMFVRdozJ5TTpN+_4thiDRBJBFq8gGtuRVYvA@mail.gmail.com>
Subject: Re: MT76x2U crashes XHCI driver on AMD Ryzen system
To:     Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>
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Sender: linux-wireless-owner@vger.kernel.org
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On Sun, Jan 13, 2019 at 11:00 AM Lorenzo Bianconi
<lorenzo.bianconi@redhat.com> wrote:
>
> >
> >
> > 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)
Tried a USB 3 port. Same result.
>
> > Could you please double check if IOMMU is enabled?
> >
>
> Have you tried to disable it? Does it make any difference?
No idea how. UEFI doesn't seem to show anything similar.

Similar bug report: https://bugzilla.kernel.org/show_bug.cgi?id=202241
>
> Regards,
> Lorenzo
>
> > It is.
> >
> > Note that this does not happen on kernel 4.15 (Ubuntu's kernel) as mt76 lacks support.
> >
> > Regards, Lorenzo
> >
> >
> >