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SubjectRE: [PATCH 0/7] net: stmmac: enable EHL SGMII
>-----Original Message-----
>From: Andrew Lunn []
>Sent: Thursday, April 25, 2019 8:38 PM
>To: Voon, Weifeng <>
>Cc: David S. Miller <>;; linux-
>; Ong, Boon Leong <>;
>Kweh, Hock Leong <>; Florian Fainelli
><>; Maxime Coquelin <>;
>Giuseppe Cavallaro <>; Jose Abreu
>Subject: Re: [PATCH 0/7] net: stmmac: enable EHL SGMII
>On Thu, Apr 25, 2019 at 07:27:51AM +0000, Voon, Weifeng wrote:
>> > > This patch-set is to enable Ethernet controller (DW Ethernet QoS and
>> > > DW Ethernet PCS) with SGMII interface in Elkhart Lake.
>> >
>> > Can the hardware also do 1000BaseX?
>> Yes, it is able to do 1000BaseX.
>I Voon
>That means you should not really hard code it to SGMII. Somebody is
>going to connect an SFP or an Ethernet switch and want to use

Hi Andrew,

The Ethernet controller consists of two ways to connect to external PHY,
RGMII and SGMII. The selection is done through soft strap.
The patch-series is to enable SGMII interface. The DW xPCS IP is
configured to operate in 1000BASE-X mode. The xPCS IP is external
connected through internal PHY interface which presents externally
as SGMII interface. To help illustrate the connection:-

<-----------------GBE Controller----------------->|<--External PHY chip-->

+----------+ +----+ +---+ +-----------------+
| EQoS | <-GMII->|xPCS|<--> | L1 | <-- SGMII --> | External GbE |
| MAC | | | |PHY| | PHY Chip |
+----------+ +----+ +---+ +-----------------+

In future, we will submit the changes for the RGMII connection that
bypasses DW xPCS.

Hope this help clarifies matter.

>At minimum, please add support for phy-mode in the device tree.
>Also, when the adjust_link callback passed to phy_connect() is called,
>you can look at the interface type to know if you need to configure it
>to SGMII or 1000BaseX. A copper PHY in an SFP module generally wants
>SGMII, but an optical module wants 1000BaseX. But to properly support
>SPFs the driver needs to swap to phylink, rather than phylib.
> Andrew

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