On Thu, Jan 22, 2026 at 09:38:17AM +0800, Chaoyi Chen wrote:

Hi Andrew,

On 1/21/2026 8:55 PM, Andrew Lunn wrote:

quoted

quoted

@@ -721,6 +719,7 @@ rgmii_phy0: ethernet-phy@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. 

quoted

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.

Please check the report. And also, check what the PHY is doing for
delays if you don't specify the property. Is it defaulting to near
2000ps?

	Andrew