Re: [PATCH v4 0/2] ARM: dts: aspeed: Add ASRock Rack B650D4U BMC

[Prasanth]

Hi Andrew,

I do not currently have the PCB layout or RGMII trace-length information,
so I cannot confirm that the PCB provides approximately 2 ns of TX delay
but no RX delay.

My hardware results are:

rgmii negotiates 1000baseT/Full, but RX traffic fails with CRC errors.
rgmii-rxid passes a 5000-packet test with no loss or RX CRC errors.
rgmii-id also passes the same test.

These results indicate that an RX delay is required, but they do not
establish whether the TX delay is provided by the PCB, MAC, or PHY. I
therefore agree that the traffic test alone is insufficient to justify
rgmii-rxid.

I have contacted ASRock Rack requesting confirmation of the RGMII timing
and PCB trace-delay configuration. I will wait for that information
before selecting the phy-mode for the next revision or making a claim
about where the TX delay is implemented.

Thanks,
Prasanth

On Mon, Aug 31, 2026 at 1:53 AM Andrew Lunn <andrew@xxxxxxx> wrote:
>
> On Sun, Aug 30, 2026 at 11:50:34PM +0530, Prasanth Kumar Padarthi wrote:
> > Add device tree support for the ASRock Rack B650D4U BMC, which is
> > based on the ASPEED AST2600 SoC.
> >
> > The series adds the board compatible and describes the BMC memory,
> > SPI NOR flash layout, UART console, and MAC0 connected to an
> > RTL8211F Ethernet PHY.
> >
> > The MAC0 RGMII timing configuration was validated on B650D4U
> > hardware. With plain "rgmii", the PHY negotiated 1000baseT/Full but
> > received no valid packets and accumulated RX CRC errors. With
> > "rgmii-rxid", a 5000-packet test completed with 0% packet loss and
> > no RX CRC errors. "rgmii-id" was also tested successfully, but the
> > additional TX delay is not required, so "rgmii-rxid" is retained.
>
> Please take a read of:
>
> https://elixir.bootlin.com/linux/v6.15/source/Documentation/devicetree/bindings/net/ethernet-controller.yaml#L287
>
> Does the PCB have 2ns of delay for TX, but notR RX?
>
>      Andrew