[PATCH] arm: dts: agilex: add U-Boot DT for socdk_nand

[dinesh.maniyam at altera.com]

From: Dinesh Maniyam <dinesh.maniyam at altera.com>

The intel/socfpga_agilex_socdk_nand device tree was added to
CONFIG_OF_LIST by
commit 044d6a800edd ("arm: socfpga: agilex: restore Multi-DTB support for NAND boot")
but the corresponding U-Boot overrides DTSI was missing.

The included socfpga_agilex-u-boot.dtsi unconditionally disables
gmac2 and enables gmac0; the NAND board variant has the opposite
wiring, so re-enable gmac2 and disable gmac0. Also clamp
max-frame-size on gmac2 to 3800, matching what the U-Boot
stmmac driver expects on this board.

Without this file, the NAND DTB packaged into the FIT image keeps
gmac2 disabled and Ethernet is unavailable on the NAND boot path.

Signed-off-by: Dinesh Maniyam <dinesh.maniyam at altera.com>
---
 .../dts/socfpga_agilex_socdk_nand-u-boot.dtsi   | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 arch/arm/dts/socfpga_agilex_socdk_nand-u-boot.dtsi

diff --git a/arch/arm/dts/socfpga_agilex_socdk_nand-u-boot.dtsi b/arch/arm/dts/socfpga_agilex_socdk_nand-u-boot.dtsi
new file mode 100644
index 00000000000..a31a26fcffb
--- /dev/null
+++ b/arch/arm/dts/socfpga_agilex_socdk_nand-u-boot.dtsi
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * U-Boot additions
+ *
+ * Copyright (C) 2025 Altera Corporation <www.altera.com>
+ */
+
+#include "socfpga_agilex_socdk-u-boot.dtsi"
+
+&gmac0 {
+	status = "disabled";
+};
+
+&gmac2 {
+	status = "okay";
+	max-frame-size = <3800>;
+};
-- 
2.43.7