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From:   Jose Abreu <Jose.Abreu@synopsys.com>
To:     Voon Weifeng <weifeng.voon@intel.com>,
        "David S . Miller" <davem@davemloft.net>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>
CC:     "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
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        "Giuseppe Cavallaro" <peppe.cavallaro@st.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Ong Boon Leong <boon.leong.ong@intel.com>
Subject: RE: [RFC,net-next,v1, 1/1] net: stmmac: Enable SERDES power up/down
 sequence
Thread-Topic: [RFC,net-next,v1, 1/1] net: stmmac: Enable SERDES power up/down
 sequence
Thread-Index: AQHWAE03JZEV2gP9CkiKXaQcDq7OzahVzGeA
Date:   Mon, 23 Mar 2020 07:46:39 +0000
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From: Voon Weifeng <weifeng.voon@intel.com>
Date: Mar/22/2020, 13:23:42 (UTC+00:00)

> This patch is to enable Intel SERDES power up/down sequence. The SERDES
> converts 8/10 bits data to SGMII signal. Below is an example of
> HW configuration for SGMII mode. The SERDES is located in the PHY IF
> in the diagram below.
>=20
> <-----------------GBE Controller---------->|<--External PHY chip-->
> +----------+         +----+            +---+           +----------+
> |   EQoS   | <-GMII->| DW | < ------ > |PHY| <-SGMII-> | External |
> |   MAC    |         |xPCS|            |IF |           | PHY      |
> +----------+         +----+            +---+           +----------+
>        ^               ^                 ^                ^
>        |               |                 |                |
>        +---------------------MDIO-------------------------+
>=20
> PHY IF configuration and status registers are accessible through
> mdio address 0x15 which is defined as intel_adhoc_addr. During D0,
> The driver will need to power up PHY IF by changing the power state
> to P0. Likewise, for D3, the driver sets PHY IF power state to P3.

I don't think this is the right approach.

You could just add a new "mdio-intel-serdes" to phy/ folder just like I=20
did with XPCS because this is mostly related with PHY settings rather than=
=20
EQoS.

Perhaps Andrew has better insight on this.

BTW, are you using the standard XPCS helpers in phy/ folder ? Is it=20
working fine for you ?

---
Thanks,
Jose Miguel Abreu