netdev - Re: [PATCH 1/2] net: phy: micrel: Add KS8851 PHY support

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Message-ID: <252db93a-f52d-a5d4-505a-bf4a82328981@denx.de>
Date:   Sun, 3 Jan 2021 19:44:33 +0100
From:   Marek Vasut <marex@...x.de>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org, Heiner Kallweit <hkallweit1@...il.com>,
        Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH 1/2] net: phy: micrel: Add KS8851 PHY support

On 1/3/21 5:55 PM, Andrew Lunn wrote:
> On Sun, Jan 03, 2021 at 01:55:22PM +0100, Marek Vasut wrote:
>> On 12/30/20 4:43 PM, Andrew Lunn wrote:
>>> On Wed, Dec 30, 2020 at 01:53:57PM +0100, Marek Vasut wrote:
>>>> The KS8851 has a reduced internal PHY, which is accessible through its
>>>> registers at offset 0xe4. The PHY is compatible with KS886x PHY present
>>>> in Micrel switches, except the PHY ID Low/High registers are swapped.
>>>
>>> Can you intercept the reads in the KS8851 driver and swap them back
>>> again? The mv88e6xxx driver does something similar. The mv88e6393
>>> family of switches have PHYs with the Marvell OUI but no device ID. So
>>> the code traps these reads and provides an ID.
>>
>> I would prefer to keep this as-is, since then the PHY driver can match on
>> these swapped IDs and discern the PHY from PHY present in the KS886x switch.
> 
> The problem is, this ID contains an OUI. Well, part of an OUI, the top
> two bits of the OUI are removed, leaving 22 bits of a 24 bit
> OUI. These OUIs are assigned to companies, well organisations. If you
> look at the reversed PHY ID, what are the 4 possible OUIs? Who are
> they assigned to? Are they ever likely to manufacture a PHY?

Are these OUIs used for anything else than identifying the PHY though ?