Re: [PATCH v2] arm64: dts: allwinner: a64: olinuxino: Fix phy-mode

[Andrew Lunn]

On Sat, Aug 22, 2026 at 08:23:53AM +0300, Roman Riabenko wrote:
> The 'rgmii' mode does not appear to describe the RGMII timing in Olimex
> A64-OlinuXino boards. The PCB layout shows that the clock and data
> traces have roughly the same lengths for both RX and TX and, thus, do
> not appear to implement the 2 ns RGMII delay or introduce any
> significant delay.
> 
> According to the KSZ9031RNX datasheet, the PHY adds a typical 1.2 ns RX
> delay and no TX delay by default. The 'rgmii-id' mode causes the PHY
> driver to enable appropriate internal RGMII delays.
> 
> Packet loss in the downlink direction is observed with the 'rgmii' mode
> and is severe enough to interfere with downloads and disrupt software
> installation. No packet loss is observed with 'rgmii-id'.
> 
> Adjusting the TX delay in the DT was found to be unnecessary with
> 'rgmii-id'.

Nice, thanks for doing a proper analysis.

> Signed-off-by: Roman Riabenko <roman@xxxxxxxxxxxx>

  Reviewed-by: Andrew Lunn <andrew@xxxxxxx>

    Andrew