HiFive unleashed A00 board has VSC8541-01 ethernet phy, this device is identified as a Revision B device as described in device identification registers. In order to use this phy in the unmanaged mode, it requires a specific reset sequence of logical 0-1-0-1 transition on the NRESET pin as documented here [1]. Currently, the bootloader (fsbl) takes care of the phy reset. If due to some reason the phy device hasn't received the reset by the prior stages before the linux macb driver comes into the picture, the MACB mii bus gets probed but the mdio scan fails and is not even able to read the phy ID registers. It gives an error message: "libphy: MACB_mii_bus: probed mdio_bus 10090000.ethernet-ffffffff: MDIO device at address 0 is missing." Thus adding the device OUI (Organizationally Unique Identifier) to the phy device node helps to probe the phy device. [1]: VSC8541-01 datasheet: https://www.mouser.com/ds/2/523/Microsemi_VSC8541-01_Datasheet_10496_V40-1148034.pdf Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@xxxxxxxxxx> --- arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts index 4a2729f..60846e8 100644 --- a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts +++ b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts @@ -88,6 +88,7 @@ phy-mode = "gmii"; phy-handle = <&phy0>; phy0: ethernet-phy@0 { + compatible = "ethernet-phy-id0007.0771"; reg = <0>; }; }; -- 2.7.4
