Messages in this thread | | | Date | Mon, 29 Aug 2022 15:09:55 +0200 | From | Andrew Lunn <> | Subject | Re: [PATCH 2/2] net: ethernet: stmicro: stmmac: dwmac-rk: Add rv1126 support |
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On Mon, Aug 29, 2022 at 06:50:42AM +0000, Anand Moon wrote: > Rockchip RV1126 has GMAC 10/100/1000M ethernet controller > via RGMII and RMII interfaces are configured via M0 and M1 pinmux. > > This patch adds rv1126 support by adding delay lines of M0 and M1 > simultaneously.
What does 'delay lines' mean with respect to RGMII?
The RGMII signals need a 2ns delay between the clock and the data lines. There are three places this can happen:
1) In the PHY 2) Extra long lines on the PCB 3) In the MAC
Generally, 1) is used, and controlled via phy-mode. A value of PHY_INTERFACE_MODE_RGMII_ID passed to the PHY driver means it will add these delays.
You don't want both the MAC and the PHY adding delays.
Andrew
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