linux-kernel - Re: [PATCH] RFC: net: phy: of phys probe/reset issue

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Date:   Wed, 28 Oct 2020 21:32:32 +0200
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>
CC:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Roger Quadros <rogerq@...com>,
        Russell King <linux@...linux.org.uk>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH] RFC: net: phy: of phys probe/reset issue

hi Andrew,

On 23/10/2020 23:10, Andrew Lunn wrote:
>> Yes there is: have your Ethernet PHY compatible string be of the form
>> "ethernetAAAA.BBBB" and then there is no need for such hacking.
>> of_get_phy_id() will parse that compatible and that will trigger
>> of_mdiobus_register_phy() to take the phy_device_create() path.
> 
> Yep. That does seem like the cleanest way to do this. Let the PHY
> driver deal with the resources it needs.

Thanks you for your comments.

huh. I gave it try and some thinking. it works as W/A, but what does it mean in the long term?

Neither Linux documentation, neither DT bindings suggest such solution in any way
(and there is *Zero* users of ""ethernet-phy-id%4x.%4x" in the current LKML).
And the main reason for this RFC is really bad customer experience while migrating to the new kernels, as
mdio reset does not support multi-phys and phy resets are not working.

Following your comments, my understanding for the long term (to avoid user's confusions) is:
"for OF case the usage of 'ethernet-phy-id%4x.%4x' compatibly is became mandatory for PHYs
to avoid PHY resets dependencies from board design and bootloader".

Which in turn means - update all reference boards by adding ""ethernet-phy-id%4x.%4x" and add
new DT board files for boards which are differ by only PHY version.

:(

-- 
Best regards,
grygorii