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Subject: Re: [PATCH v2] r8152: disable RX aggregation on Dell TB16 dock
From:   Kai Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <20180118.095022.1121845945987753430.davem@davemloft.net>
Date:   Fri, 19 Jan 2018 00:57:24 +0800
Cc:     Hayes Wang <hayeswang@realtek.com>, gregkh@linuxfoundation.org,
        linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, mario.limonciello@dell.com,
        nic_swsd@realtek.com
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Message-Id: <55F628DA-8B95-4FA8-B160-4A3B9D03D6B8@canonical.com>
References: <20180116084627.12638-1-kai.heng.feng@canonical.com>
 <20180117.153930.330864749049561139.davem@davemloft.net>
 <0835B3720019904CB8F7AA43166CEEB2D2E16D63@RTITMBSV06.realtek.com.tw>
 <20180118.095022.1121845945987753430.davem@davemloft.net>
To:     David Miller <davem@davemloft.net>
Sender: linux-kernel-owner@vger.kernel.org
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> On 18 Jan 2018, at 10:50 PM, David Miller <davem@davemloft.net> wrote:
> 
> From: Hayes Wang <hayeswang@realtek.com>
> Date: Thu, 18 Jan 2018 03:04:08 +0000
> 
>> [...]
>>>> r8153 on Dell TB15/16 dock corrupts rx packets.
>>>> 
>>>> This change is suggested by Realtek. They guess that the XHCI
>>>> controller doesn't have enough buffer, and their guesswork is correct,
>>>> once the RX aggregation gets disabled, the issue is gone.
>>>> 
>>>> ASMedia is currently working on a real sulotion for this issue.
>>>> 
>>>> Dell and ODM confirm the bcdDevice and iSerialNumber is unique for TB16.
>>>> 
>>>> Note that TB15 has different bcdDevice and iSerialNumber, which are
>>>> not unique values. If you still have TB15, please contact Dell to
>>>> replace it with TB16.
>> 
>> Excuse me. I don't understand why this patch is for specific USB nic rather than xHCI.
>> It seems to make the specific USB nic working and the other ones keeping error.
> 
> Well, are we sure that the device being in the TB16 dock doesn't
> contribute to the issue as well?

This is what vendors concluded for now. The very same NIC on WD15 doesn’t
have the issue.

> 
> If the problem only shows up with XHCI and this dock, then this patch
> was the appropriate way to deal with the problem for now.