netdev - Re: [PATCH] r8152: disable rx checksum offload on Dell TB dock

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Date:   Fri, 24 Nov 2017 11:44:02 +0800
From:   Kai Heng Feng <kai.heng.feng@...onical.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     David Miller <davem@...emloft.net>, hayeswang@...ltek.co,
        linux-usb@...r.kernel.org, netdev@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Mario Limonciello <mario.limonciello@...l.com>
Subject: Re: [PATCH] r8152: disable rx checksum offload on Dell TB dock



> On 23 Nov 2017, at 5:24 PM, Greg KH <gregkh@...uxfoundation.org> wrote:
> 
> On Thu, Nov 23, 2017 at 04:53:41PM +0800, Kai Heng Feng wrote:
>> 
>> What I want to do here is to finding this connection:
>> Realtek r8153 <-> SMSC hub (USD ID: 0424:5537) <-> 
>> ASMedia XHCI controller (PCI ID: 1b21:1142).
>> 
>> Is there a safer way to do this?
> 
> Nope!  You can't do that at all from within a USB driver, sorry.  As you
> really should not care at all :)

Got it :)

The r8153 in Dell TB dock has version information, RTL_VER_05.
We can use it to check for workaround, but many working RTL_VER_05 devices
will also be affected.
Do you think it’s an acceptable compromise?

>> I have a r8153 <-> USB 3.0 dongle which work just fine. I can’t find any 
>> information to differentiate them. Hence I want to use the connection to
>> identify if r8153 is on a Dell TB dock.
> 
> Are you sure there is nothing different in the version or release number
> of the device?  'lsusb -v' shows the exact same information for both
> devices?

Yes. I attached `lsusb -v` for r8153 on Dell TB dock, on a RJ45 <-> USB 3.0 dongle,
and on a RJ45 <-> USB Type-C dongle.

>> Yes. From what I know, ASMedia is working on it, but not sure how long it
>> will take. In the meantime, I’d like to workaround this issue for the users.
> 
> Again, it's a host controller bug, it should be fixed there, don't try
> to paper over the real issue in different individual drivers.
> 
> I think I've seen various patches on the linux-usb list for this
> controller already, have you tried them?

Yes. These patches are all in mainline Linux now.

>> Actually no.
>> I just plugged r8153 dongle into the same hub, surprisingly the issue
>> doesn’t happen in this scenario.
> 
> Then something seems to be wrong with the device itself, as that would
> be the same exact electrical/logical path, right?

I have no idea why externally plugged one doesn’t have this issue.
Maybe it’s related how it’s wired inside the Dell TB dock...

Kai-Heng


Download attachment "lsusb-a" of type "application/octet-stream" (6414 bytes)

Download attachment "lsusb-c" of type "application/octet-stream" (6484 bytes)

Download attachment "lsusb-dock" of type "application/octet-stream" (6414 bytes)


> thanks,
> 
> greg k-h