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Date: Wed, 29 May 2024 16:28:16 +0200
From: Andrew Lunn <andrew@lunn.ch>
To: Sneh Shah <quic_snehshah@quicinc.com>
Cc: "Russell King (Oracle)" <linux@armlinux.org.uk>,
	Andrew Halaney <ahalaney@redhat.com>, Vinod Koul <vkoul@kernel.org>,
	Bhupesh Sharma <bhupesh.sharma@linaro.org>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>, netdev@vger.kernel.org,
	linux-arm-msm@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
	kernel@quicinc.com
Subject: Re: [PATCH net-next] net: stmmac: dwmac-qcom-ethqos: Add support for
 2.5G SGMII
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> Qualcomm ethernet HW supports 2.5G speed in overclocked SGMII mode.
> we internally term it as OCSGMII.

So it still does SGMII inband signalling? Not 2500BaseX signalling? It
is not actually compatible with 2500BaseX?

> End goal of these patches is to enable SGMII with 2.5G speed support.
> The patch in these series enabled up SGMII with 2.5 for cases where we
> don't have external phy. ( mac-to-mac connectivity)

So the other end needs to be an over clocked SGMII MAC, not 2500BaseX?

> The new patch posted extends this for the case when the MAC has an
> external phy connected. ( hence we are advertising fr 2.5G speed by adding
> 2500BASEX as supported interface in phylink)

And i assume it does not actually work against a true 2500BaseX
device, because it is doing SGMII inband signalling?
 
Hence Russell frustration with the whole 2.5G mess....

      Andrew