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Subject: Re: r8152: data corruption in various scenarios
From:   Kai Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <469a41ea-e97c-23d2-d129-68aad5585fec@pobox.com>
Date:   Mon, 7 Jan 2019 03:14:09 +0800
Cc:     Ansis Atteka <aatteka@nicira.com>,
        Hayes Wang <hayeswang@realtek.com>,
        David Miller <davem@davemloft.net>,
        "greg@kroah.com" <greg@kroah.com>,
        "romieu@fr.zoreil.com" <romieu@fr.zoreil.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        nic_swsd <nic_swsd@realtek.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        Mario Limonciello <mario.limonciello@dell.com>
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To:     Mark Lord <mlord@pobox.com>
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> On Jan 5, 2019, at 10:14 PM, Mark Lord <mlord@pobox.com> wrote:
> 
> A couple of years back, I reported data corruption resulting from
> a change in kernel 3.16 which enabled hardware checksums in the r8152 driver.
> This was happening on an embedded system that was using a r8152 USB dongle.
> 
> At the time, it was very difficult to figure out what could possibly be causing it,
> other than that re-enabling software checksums prevented corrupted packets from
> resulting in more serious issues.
> 
> Since that time, more and more reports of similar corruption and issues
> have been trickling in.  Eg.
> 
>   https://lore.kernel.org/patchwork/patch/873920/
> 
> Note that there are reports in the thread above that the issues
> are not limited to only the built-in ethernet chip of the dock.
> 
> There is even now a special hack in the upstream r8152.c to attempt to detect
> a Dell TB16 dock and disable RX Aggregation in the driver to prevent such issues.
> 
> Well.. I have a WD15 dock, not a TB16, and that same hack also catches my dock
> in its net:
> 
>    [5.794641] usb 4-1.2: Dell TB16 Dock, disable RX aggregation

The serial should be unique according to Dell.

> 
> So one issue is that the code is not correctly identifying the dock,
> and the WD15 is claimed to be immune from the r8152 issues.

The WD15 I tested didn't use that serial number though...

> 
> One of the symptoms of the r8152 issue, reported by Ansis Atteka,
> were messages like this:
> 
>   xhci_hcd 0000:39:00.0: ERROR Transfer event TRB DMA ptr not part of current TD ep_index 13
> comp_code 1

This is probably an xHC bug. A similar issue is fixed by commit 9da5a1092b13
("xhci: Bad Ethernet performance plugged in ASM1042A host”). 

> 
> I just got that exact message above, with the r8152 in my 1-day old WD15 dock,
> with the TB16 "workaround" enabled in Linux kernel 4.20.0.

Is the xHC WD15 connected an ASMedia one?

Kai-Heng

> 
> From this I conclude that the workaround is not 100% complete yet.
> -- 
> Mark Lord
> Real-Time Remedies Inc.
> mlord@pobox.com