netdev - Re: [PATCH v2 2/4] dt-bindings: net: qcom: Add binding for shared mdio bus

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Message-ID: <7696bcd8ca594b1da683b437197b4ddf@HXTBJIDCEMVIW02.hxtcorp.net>
Date:   Wed, 19 Sep 2018 09:19:19 +0000
From:   "Wang, Dongsheng" <dongsheng.wang@...-semitech.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     Florian Fainelli <f.fainelli@...il.com>,
        "timur@...nel.org" <timur@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "Zheng, Joey" <yu.zheng@...-semitech.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] dt-bindings: net: qcom: Add binding for shared
 mdio bus

On 2018/9/18 20:35, Andrew Lunn wrote:
>>> If you want to describe the MDIO controller, then you embed a mdio
>>> subnode into your Ethernet MAC node:
>>>
>>>  emac0: ethernet@...20000 {
>>> 	mdio {
>>> 		#address-cells = <1>;
>>> 		#size-cells = <0>;
>>>
>>> 		phy0: ethernet-phy@0 {
>>> 			reg = <0>;
>>> 		};
>>> 	};
>>> };
>>>
>>> And then each Ethernet MAC controller refers to their appropriate PHY
>>> device tree node using a phy-handle property to point to either their
>>> own MDIO controller, or another MAC's MDIO controller.
>> Sorry, I do not understand how phy-handle point to MDIO controller,
>> because phy-handle is defined to point to a phy.
> The MAC driver does not care what MDIO controller a PHY is on. All you
> need to do to register the PHY is:

Yes, these are all things that must be done, and emac driver will
connect phy when mac up.
If we had a separate MDIO controller, the MAC would not care about MDIO
bus. But MDIO is integrated within the EMAC, and emac driver maintains
the mdio.

Each EMAC do their mdio register/unregister. But in the shared scenario,
the EMACs that use the shared bus do not need to create an MDIO and
cannot release the Shared bus.

In device tree environment as you and Florian said. Just use phy-handle
get the phy_node.
The EMAC would not care about the phy come from which MDIO bus because
the phy device gets from the device_node match(phy-handle). And if the
phy_dev cannot get through phy_node means, the mdio bus is not ready.

But ACPI environment my understand is this:
First method. EMAC driver gets the shared MDIO bus, and maintain it.
The second way, EMAC match the phy_dev from the name.
These patch series try to use the FIRST way. Now I prefer to use the
second way to do the shared function.

I will rework this patchset and maybe patches will be a delay for a few
days.

Cheers,
Dongsheng
> 	phy_node = of_parse_phandle(np, "phy-handle", 0);
> 	phy_interface = of_get_phy_mode(np);
> 	phydev = of_phy_connect(dev, phy_node,
>                                 &handle_link_change, 0,
>                                 phy_interface);
>
> 	Andrew
>