Re: [PATCH 3/6] arm64: dts: qcom: ipq5332: Add MDIO device tree

From: Andrew Lunn
Date: Tue Jan 16 2024 - 17:57:11 EST


> Another one is the MDIO slave(gpio25, 26), which is dedicated
> for receiving the back pressure signal from the connected Ethernet switch
> device QCA8386.
>
> There is a MDIO master block integrated in QCA8386 switch device, this
> integrated MDIO master is dedicated for generating the back
> pressure signal to IPQ5332 SoC.
>
> This MDIO slave block of IPQ5322 just needs to configure these PIN
> mux for MDC and MDIO PINs. No additional driver is needed for this MDIO
> slave block of IPQ5332.

So there is a proprietary protocol running over the MDIO bus? And its
completely implemented in hardware in the slave block? Is this even
MDIO? Does it use c22 or c45 bus transactions? How is the slave
address configured, or is that also hard coded?

Andrew