Nucleo U385RG-Q arduino_spi dts description is wrong

[smtc-omu]

Describe the bug

In Nucleo U385RG-Q's boards/st/nucleo_u385rg_q/arduino_r3_connector.dtsi, the arduino_spi label points to spi3 node. Looking at spi3 node definition in boards/st/nucleo_u385rg_q/nucleo_u385rg_q.dts, we have

&spi3 {
	pinctrl-0 = <&spi3_nss_pa15 &spi3_sck_pb3
		     &spi3_miso_pb4 &spi3_mosi_pb5>;
	pinctrl-names = "default";
	status = "okay";
};

However, in ST's Nucleo U385RG-Q's schematic on ST's website, the pinout is different:
Arduino pin D11 (MOSI) -> PA7
Arduino pin D12 (MISO) -> PA6
Arduino pin D13 (SCK) -> PA5
Which have to be used with spi1. The NSS signal can be used on PA4. So, in arduino_r3_connector.dtsi, there should be

arduino_spi: &spi1 {};

And on nucleo_u385rg_q.dts:

&spi1 {
	pinctrl-0 = <&spi1_nss_pa4 &spi1_sck_pa5
		     &spi1_miso_pa6 &spi1_mosi_pa7>;
	pinctrl-names = "default";
	status = "okay";
};

should be added. The spi3 node can stay unchanged.

Regression

• This is a regression.

Steps to reproduce

1. On any application using arduino_spi node label and compiled for nucleo_u385rg_q, try to use the SPI line on Arduino connector D11-D12-D13.

Relevant log output

Impact

Functional Limitation – Some features not working as expected, but system usable.

Environment

• OS: Tested on Unix (should not matter)
• Toolchain: v0.17.4 (should not matter)
• Zephyr version: still present in V4.2.1

Additional Context

It is assumed that spi3 pins (PB3/PB4/PB5) might have been routed on Arduino SPI connector on a previous revision of the board.

[github-actions]

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[erwango]

@smtc-omu Thanks for raising this issue. Since you seem to have a fix, don't hesitate to contribute it!