HiFive Unleashed is having VSC8541-01 ethernet phy device and requires a specific reset sequence of 0-1-0-1 in order to use it in unmanaged mode. This series addresses a corner case where phy reset is not handled by boot stages prior to linux. Somewhat similar unreliable phy probe failure was reported and discussed here [1]. The macb driver fails to detect the ethernet phy device if the bootloader doesn't provide a proper reset sequence to the phy device or the phy itself is in some invalid state. Currently, the FSBL is resetting the phy device, and so there is no issue observed in the linux network setup. The series is based on linux-5.7-rc2. Patch 1: Add the OUI to the phy dt node to fix issue of missing mdio device Patch 2 and 3: Resetting phy needs GPIO support so add to dt and defconfig. Patch 4: Add dt binding for OUI introduced in patch 1. [1] https://lkml.org/lkml/2018/11/29/154 To reproduce the issue: 1. Comment out VSC8541 reset sequence in fsbl/main.c from within the freedom-u540-c000-bootloader. 2. Build and add fsbl.bin to micro sdcard. Boot the board and bootlog will show network setup failure messages as: [ 1.069474] libphy: MACB_mii_bus: probed [ 1.073092] mdio_bus 10090000.ethernet-ffffffff: MDIO device at address 0 is missing ..... [ 1.979252] macb 10090000.ethernet eth0: Could not attach PHY (-19) 3. Now apply the series build, and boot kernel. 4. MACB and VSC8541 driver get successfully probed and the network is set without any failure. So irrespective of whether the prior stages handle the phy reset sequence, the probing is successful in both the cases of cold boot and warm boot. Sagar Shrikant Kadam (4): dts: phy: fix missing mdio device and probe failure of vsc8541-01 device dts: phy: add GPIO number and active state used for phy reset riscv: defconfig: enable gpio support for HiFive Unleashed dt-bindings: net: phy: extend dt binding for VSC8541 ethernet-phy Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt | 3 +++ arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts | 2 ++ arch/riscv/configs/defconfig | 2 ++ 3 files changed, 7 insertions(+) -- 2.7.4
