Re: [PATCH v3 2/7] arm64: dts: allwinner: orangepi-zero2: Let the PHY add the RX delay

[Chen-Yu Tsai]

On Thu, Nov 12, 2026 at 5:22 PM Arun Iyengar via B4 Relay
<devnull+aiyengar1990.gmail.com@xxxxxxxxxx> wrote:
>
> From: Arun Iyengar <aiyengar1990@xxxxxxxxx>
>
> The Orange Pi Zero2 describes its RTL8211F link as "rgmii", with the
> whole RX clock delay (3100 ps, the maximum the H616 EMAC syscon can
> add) inserted by the MAC. With "rgmii" the Realtek PHY driver also
> clears the PHY's own RX delay bit, so RX sampling relies on the MAC
> delay alone and sits at the edge of the window.
>
> On the board this shows up as intermittent boots with a dead receive
> path, after cold and warm resets alike: the link comes up at
> 1000/full and frames are transmitted and seen by the peer, but nothing
> is ever received and the EMAC raises no RX interrupt. All EMAC clock,
> pinmux, drive strength and syscon registers are the same on good and
> bad boots. On a bad boot, setting the PHY RX delay bit and clearing
> the syscon RX delay restores reception at once, without a link reset.
>
> Use "rgmii-rxid" (RX delay in the PHY, none in the MAC), as the Orange
> Pi Zero3 with the same PHY already does, and as the vendor BSP does.

Flagged by my review agent, and documents reviewed by me:

The Orange Pi Zero3 uses a different PHY, but the pin strapping is the
same, and has the same meaning: the PHY provides the RX delays, while
the MAC provides the TX delays.

I can fix up the commit message when applying.

> The 700 ps MAC TX delay is kept. With this change 10 of 10 cold boots
> had a working receive path.
>
> Fixes: 5a378f9f2b15 ("arm64: dts: allwinner: h616: Add OrangePi Zero 2 board support")
> Signed-off-by: Arun Iyengar <aiyengar1990@xxxxxxxxx>
> ---
>  arch/arm64/boot/dts/allwinner/sun50i-h616-orangepi-zero2.dts | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h616-orangepi-zero2.dts b/arch/arm64/boot/dts/allwinner/sun50i-h616-orangepi-zero2.dts
> index f2e3300e078a..1fdf2d3c1a87 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-h616-orangepi-zero2.dts
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-h616-orangepi-zero2.dts
> @@ -18,9 +18,9 @@ &cpu0 {
>  };
>
>  &emac0 {
> -       allwinner,rx-delay-ps = <3100>;
>         allwinner,tx-delay-ps = <700>;
> -       phy-mode = "rgmii";
> +       /* RX delay is added by the PHY, TX delay by the EMAC */
> +       phy-mode = "rgmii-rxid";
>         phy-supply = <&reg_dcdce>;
>  };
>
>
> --
> 2.55.0
>
>