[PATCH 3/5] ARM: dts: imx6qdl-sr-som: add support for alternate phy addresses

[Josua Mayer]

The Cubox has an unstable phy address - which can appear at either
address 0 (intended) or 4 (unintended).

SoM revision 1.9 has replaced the ar8035 phy with an adin1300, which
will always appear at address 1.

Change the reg property of the phy node to the magic value 0xffffffff,
which indicates to the generic phy driver that all addresses should be
probed. That allows the same node (which is pinned by phy-handle) to match
either the AR8035 PHY at both possible addresses, as well as the new one
at address 1.
Also add the new adi,phy-output-clock property for enabling the 125MHz
clock used by the fec ethernet controller, as submitted to Linux [1].

Linux solves this problem differently:
For the ar8035 phy it will probe both phy nodes in device-tree in order,
and use the one that succeeds. For the new adin1300 it expects U-Boot to
patch the status field in the DTB before booting

While at it also sync the reset-delay with the upstream Linux dtb.

[1] https://patchwork.kernel.org/project/netdevbpf/patch/20220428082848.12191-4-josua@solid-run.com/

Signed-off-by: Josua Mayer <josua at solid-run.com>
---
 arch/arm/dts/imx6qdl-sr-som.dtsi | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/arm/dts/imx6qdl-sr-som.dtsi b/arch/arm/dts/imx6qdl-sr-som.dtsi
index b06577808f..c20bed2721 100644
--- a/arch/arm/dts/imx6qdl-sr-som.dtsi
+++ b/arch/arm/dts/imx6qdl-sr-som.dtsi
@@ -55,7 +55,13 @@
 	pinctrl-0 = <&pinctrl_microsom_enet_ar8035>;
 	phy-handle = <&phy>;
 	phy-mode = "rgmii-id";
-	phy-reset-duration = <2>;
+
+	/*
+	 * The PHY seems to require a long-enough reset duration to avoid
+	 * some rare issues where the PHY gets stuck in an inconsistent and
+	 * non-functional state at boot-up. 10ms proved to be fine .
+	 */
+	phy-reset-duration = <10>;
 	phy-reset-gpios = <&gpio4 15 GPIO_ACTIVE_LOW>;
 	status = "okay";
 
@@ -64,8 +70,15 @@
 		#size-cells = <0>;
 
 		phy: ethernet-phy at 0 {
-			reg = <0>;
+			/*
+			 * The PHY can appear either:
+			 * - AR8035: at address 0 or 4
+			 * - ADIN1300: at address 1
+			 * Actual address being detected at runtime.
+			 */
+			reg = <0xffffffff>;
 			qca,clk-out-frequency = <125000000>;
+			adi,phy-output-clock = "125mhz-free-running";
 		};
 	};
 };
-- 
2.34.1