[PATCH 1/3] arm64: dts: rockchip: Change gmac phy-mode to rgmii-id for rk3576 evb1
Chaoyi Chen
kernel at airkyi.com
Wed Jan 21 17:38:17 PST 2026
Hi Andrew,
On 1/21/2026 8:55 PM, Andrew Lunn wrote:
>> @@ -721,6 +719,7 @@ rgmii_phy0: ethernet-phy at 1 {
>> reset-assert-us = <20000>;
>> reset-deassert-us = <100000>;
>> reset-gpios = <&gpio2 RK_PB5 GPIO_ACTIVE_LOW>;
>> + tx-internal-delay-ps = <1950>;
>
> The PHY should add 2000ps, as required by the RGMII standard. The
> difference is so small there is no need for tx-internal-delay.
>
Thank you for the clarification. I chose 1950 here because I find that
the MotorComm yt8xxx Ethernet PHY binding only offer the options of
1950 or 2100.
> In most cases, 'rmgii-id' should be sufficient, unless the PCB is
> badly designed.
>
I suspect the ROCK 4D board might be an exception. Sebastian once
reported that it wouldn't work properly under "rgmii-id". Well, I'm
not sure what strategy to adopt in this case.
--
Best,
Chaoyi
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