RE: [PATCH v6] r8152: Add support for setting pass through MAC address on RTL8153-AD

[Mario_Limonciello]

> -----Original Message-----
> From: Limonciello, Mario
> Sent: Tuesday, June 14, 2016 5:27 PM
> To: 'David Miller' <davem@xxxxxxxxxxxxx>; pali.rohar@xxxxxxxxx
> Cc: gregkh@xxxxxxxxxxxxxxxxxxx; andrew@xxxxxxx;
> hayeswang@xxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> anthony.wong@xxxxxxxxxxxxx
> Subject: RE: [PATCH v6] r8152: Add support for setting pass through MAC
> address on RTL8153-AD
> 
> > -----Original Message-----
> > From: David Miller [mailto:davem@xxxxxxxxxxxxx]
> > Sent: Tuesday, June 14, 2016 1:35 PM
> > To: pali.rohar@xxxxxxxxx
> > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; andrew@xxxxxxx; Limonciello, Mario
> > <Mario_Limonciello@xxxxxxxx>; hayeswang@xxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> > usb@xxxxxxxxxxxxxxx; anthony.wong@xxxxxxxxxxxxx
> > Subject: Re: [PATCH v6] r8152: Add support for setting pass through MAC
> > address on RTL8153-AD
> >
> > From: Pali Rohár <pali.rohar@xxxxxxxxx>
> > Date: Tue, 14 Jun 2016 18:47:36 +0200
> >
> > > You have never seen two ethernet cards with same MAC addresses?
> Right
> > I
> > > have not seen two USB, but there is non zero chance that could happen.
> >
> > It would be an error scenerio, and something to be avoided.
> >
> > It is a valid and correct assumption that one is able to put
> > several devices at the same time on the same physical network
> > and expect it to work.
> >
> > The behavior added by the change in question invalidates that.
> >
> > I'm trying to consider the long term aspects of this, which is that if
> > more devices adopt this scheme we're in trouble if we blindly
> > interpret the MAC address in this way.
> >
> 
> Do you mean if other manufacturers start to ship devices with
> RTL8135-AD's w/ this pass through bit set and people start to try to
> mix and match?
> 
> > This firmware MAC property facility seems to be designed with only an
> > extremely narrow use case being considered.
> 
> Yes, as I understand it this is the reason that it's only on such specific devices
> that the mac address pass through bit is actually set on the efuse.

David,

Did you have any more thoughts about this?  I'm happy to make some other
adjustments to the patch, if you have some recommendations.