Subject: Re: [PATCH v2 1/3] net: phy: at803x: add QCA8084 ethernet phy support

From: Maxime Chevallier <[email-masked]>
Date: Thu, 9 Nov 2023 10:16:18 +0100

Hello,

On Thu, 9 Nov 2023 16:32:36 +0800
Jie Luo <[email-masked]> wrote:

[...]

> > What I understand from this is that this PHY can be used either as a
> > switch, in which case port 4 would be connected to the host interface
> > at up to 2.5G, or as a quad-phy, but since it uses QUSGMII the link
> > speed would be limited to 1G per-port, is that correct ?  
> 
> When the PHY works on the interface mode QUSGMII for quad-phy, all 4
> PHYs can support to the max link speed 2.5G, actually the PHY can
> support to max link speed 2.5G for all supported interface modes
> including qusgmii and sgmii.

I'm a bit confused then, as the USGMII spec says that Quad USGMII really
is for quad 10/100/1000 speeds, using 10b/8b encoding.

Aren't you using the USXGMII mode instead, which can convey 4 x 2.5Gbps
 with 66b/64b encoding ?

Thanks,

Maxime