On Tue, Mar 18, 2025 at 11:00:27AM +0000, Jacky Chou wrote: > Hi Andrew, > > Thank you for your reply. > > > > phy-mode = "rgmii"; > > > phy-handle = <ðphy2>; > > > > > > + tx-internal-delay-ps = <8>; > > > + rx-internal-delay-ps = <4>; > > > + > > > > Ideally you want: > > > > phy-mode = "rgmii-id"; > > tx-internal-delay-ps = <0>; > > rx-internal-delay-ps = <0>; > > > > Since 'rgmii-id' correctly describes the hardware. > > I still confuse about ethernet-controller.yaml. > It lists 'rgmi', 'rgmii-rxid', 'rgmii-txid' and 'rgmii-id'. DT describes the board. Does the board add the 2ns delay via extra long clock lines? If yes, use rgmii. If the MAC/PHY pair need to add the 2ns delay, use rgmii-id. If the MAC/PHY pair is adding the delay, the DT says nothing about how they add the delay. The general rule is the PHY adds the delay. If you look at drivers/net/phy/*.c, every PHY that implements RGMII support both PHY_INTERFACE_MODE_RGMII_ID and PHY_INTERFACE_MODE_RGMII. There is no reason not to follow ever other MAC/PHY pair and have the PHY add the delay. The MAC can then do fine tuning if needed, adding small delays. Andrew
