Ethernet on STM32MP157A with PHY AR8035 no PHY found

[jhi]

I have a problem to get the ethernet to work with the PHY AR8035 (Atheros). The board is from MYiR (MYC-YA157C-V2), but they are only providing yocto based image and I'm doing my work with buildroot. I'm using the bootlin buildroot branch: st/2021.02 https://github.com/bootlin/buildroot.git

The kernel can't find MDIO: mdio_bus stmmac-0: MDIO device at address 6 is missing.

The funny thing is, if I first boot the board from eMMC where the original image from MYiR is flashed, and afterwards, without switching power off, I start my image from the sdcard, the ethernet works. I guess this means that some register value is wrong, but I don't know where to start look. This also means that address 6 for the MDIO is also correct.

On TF-A I have CLK_ETH_DISABLED, because the 125MHz is coming from the PHY.

Below is the device tree for the kernel (CONFIG_AT803X_PHY=y is set):

&ethernet0 {
	interrupts-extended = <&intc GIC_SPI 61 IRQ_TYPE_LEVEL_HIGH>,
						<&intc GIC_SPI 62 IRQ_TYPE_LEVEL_HIGH>,
						<&exti 70 1>;
	interrupt-names = "macirq",
				"eth_wake_irq",
				"stm32_pwr_wakeup";
 
	clock-names = "stmmaceth",
				"mac-clk-tx",
				"mac-clk-rx",
				"eth-ck",
				"ethstp";
 
	clocks = <&rcc ETHMAC>,
			<&rcc ETHTX>,
			<&rcc ETHRX>,
			<&rcc ETHCK_K>,
			<&rcc ETHSTP>;
					
	status = "okay";
	pinctrl-0 = <&eth1_pins_mx>;
	pinctrl-1 = <&eth1_sleep_pins_mx>;
	pinctrl-names = "default", "sleep";
	phy-mode = "rgmii";
	max-speed = <1000>;
	phy-handle = <&phy0>;
	nvmem-cells = <&ethernet_mac_address>;
	nvmem-cell-names = "mac-address";
 
	mdio0 {
		#address-cells = <1>;
		#size-cells = <0>;
		compatible = "snps,dwmac-mdio";
		phy0: ethernet-phy@6 {
			reg = <6>;
			qca,clk-out-frequency = <125000000>;
 qca,clk-out-strength = <AR803X_STRENGTH_FULL>;
			reset-assert-us = <1000>;
			reset-deassert-us = <2000>; 
			reset-gpios = <&gpiog 0 GPIO_ACTIVE_LOW>;
		};
	};
};

I have added the "eth-ck", because I read somewhere that it would be needed on all cases (it doesn't also work without it). Do I need to enable something else on TF-A or in u-boot?

[jhi]

The u-boot is v2020.10-stm32mp-r2. It doesn't have any of the functions on your patch (your patch is actually removing all the stuff, but I guess it should add those?).

[OlivierK]

Patch is already present in DV3.1 but you need to apply it if not already done,

for p in `ls -1 ../*.patch`; do patch -p1 < $p; done

indeed the patch is removing the code because reset is handled by the phy driver instead of the ethernet driver.

In drivers/net/dwc_eth_qos.c:

you should have

static struct eqos_ops eqos_stm32_ops = {

...

    .eqos_stop_resets = eqos_null_ops,

    .eqos_start_resets = eqos_null_ops,

...

}

... and reset gpio is handled in /driver/net/eth-phy-uclass.c

[jhi]

Then I have this patch already.