netdev - Re: [PATCH net-next] net: phy: meson-gxl: support more G12A-internal PHY versions

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Message-ID: <51abd8ca-8172-edfa-1c18-b1e48231f316@linaro.org>
Date:   Sun, 15 Jan 2023 19:43:47 +0100
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Cc:     Russell King - ARM Linux <linux@...linux.org.uk>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>
Subject: Re: [PATCH net-next] net: phy: meson-gxl: support more G12A-internal
 PHY versions

Hi Heiner,

Le 15/01/2023 à 18:09, Heiner Kallweit a écrit :
> On 15.01.2023 17:57, Andrew Lunn wrote:
>> On Sun, Jan 15, 2023 at 04:19:37PM +0100, Heiner Kallweit wrote:
>>> On my SC2-based system the genphy driver was used because the PHY
>>> identifies as 0x01803300. It works normal with the meson g12a
>>> driver after this change.
>>> Switch to PHY_ID_MATCH_MODEL to cover the different sub-versions.
>>
>> Hi Heiner
>>
>> Are there any datasheets for these devices? Anything which documents
>> the lower nibble really is a revision?
>>
>> I'm just trying to avoid future problems where we find it is actually
>> a different PHY, needs its own MATCH_EXACT entry, and then we find we
>> break devices using 0x01803302 which we had no idea exists, but got
>> covered by this change.
>>
> The SC2 platform inherited a lot from G12A, therefore it's plausible
> that it's the same PHY. Also the vendor driver for SC2 gives a hint
> as it has the following compatible for the PHY:
> 
> compatible = "ethernet-phy-id0180.3301", "ethernet-phy-ieee802.3-c22";
> 
> But you're right, I can't say for sure as I don't have the datasheets.

On G12A (& GXL), the PHY ID is set in the MDIO MUX registers,
please see:
https://elixir.bootlin.com/linux/latest/source/drivers/net/mdio/mdio-mux-meson-g12a.c#L36

So you should either add support for the PHY mux in SC2 or check
what is in the ETH_PHY_CNTL0 register.

Neil

> 
>> 	Andrew
> 
> Heiner