netdev - Re: [PATCH] of: of_mdio: Handle properties for non-phy mdio devices

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Message-ID: <YCvDVEvBU5wabIx7@lunn.ch>
Date:   Tue, 16 Feb 2021 14:06:28 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Nathan Rossi <nathan@...hanrossi.com>
Cc:     netdev@...r.kernel.org, Nathan Rossi <nathan.rossi@...i.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH] of: of_mdio: Handle properties for non-phy mdio devices

On Mon, Feb 15, 2021 at 07:02:18AM +0000, Nathan Rossi wrote:
> From: Nathan Rossi <nathan.rossi@...i.com>
> 
> The documentation for MDIO bindings describes the "broken-turn-around",
> "reset-assert-us", and "reset-deassert-us" properties such that any MDIO
> device can define them. Other MDIO devices may require these properties
> in order to correctly function on the MDIO bus.
> 
> Enable the parsing and configuration associated with these properties by
> moving the associated OF parsing to a common function
> of_mdiobus_child_parse and use it to apply these properties for both
> PHYs and other MDIO devices.

Hi Nathan

What device are you using this with?

The Marvell Switch driver does its own GPIO reset handling. It has a
better idea when a hardware reset should be applied than what the
phylib core has. It will also poll the EEPROM busy bit after a
reset. How long a pause you need after the reset depends on how full
the EEPROM is.

And i've never had problems with broken-turn-around with Marvell
switches.

Given the complexity of an Ethernet switch, it is probably better if
it handles its own reset.

     Andrew