Re: [PATCH 1/3 v3] net: usb: r8152: Check used MAC passthrough address

From: Andrew Lunn <andrew@lunn.ch>
To: Hayes Wang <hayeswang@realtek.com>
Cc: Aaron Ma <aaron.ma@canonical.com>,
	"Limonciello, Mario" <Mario.Limonciello@amd.com>,
	Henning Schild <henning.schild@siemens.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	Oliver Neukum <oneukum@suse.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"tiwai@suse.de" <tiwai@suse.de>
Subject: Re: [PATCH 1/3 v3] net: usb: r8152: Check used MAC passthrough address
Date: Thu, 27 Jan 2022 13:53:06 +0100	[thread overview]
Message-ID: <YfKVslNusCMMCmgp@lunn.ch> (raw)
In-Reply-To: <5b94f064bd5c48589ea856f68ac0e930@realtek.com>

On Thu, Jan 27, 2022 at 08:06:20AM +0000, Hayes Wang wrote:
> Aaron Ma <aaron.ma@canonical.com>
> > Sent: Thursday, January 27, 2022 10:52 AM
> [...]
> > Hi all,
> > 
> > Realtek 8153BL can be identified by the following code from Realtek Outbox
> > driver:
> > } else if (tp->version == RTL_VER_09 && (ocp_data & BL_MASK)) {
> > 
> > I will suggest Realtek to send out this change for review.
> 
> I don't think the feature of MAC passthrough address is maintained
> by Realtek. Especially, there is no uniform way about it. The
> different companies have to maintain their own ways by themselves.
> 
> Realtek could provide the method of finding out the specific device
> for Lenovo. You could check USB OCP 0xD81F bit 3. For example,
> 
> 	ocp_data = ocp_read_byte(tp, MCU_TYPE_USB, USB_MISC_1);
> 	if (tp->version == RTL_VER_09 && (ocp_data & BIT(3))) {
> 		/* This is the RTL8153B for Lenovo. */
> 	}

Is there a documented meaning for this bit? Realtek have allocated
this bit to Lenovo?

Why is it guaranteed that no other devices manufactured by anybody
else will not have this bit set? That is the real question here. Does
this give false positive where you break the networking for some
random USB dongle.

     Andrew