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The pin TXD /dev/ttyS3 doesn't work

Problem description

The pin TXD (PA7/S16) on serial port /dev/ttyS3 doesn't work.

Solution

Change on arch/arm/boot/dts/acme-aria.dts this section:

spi0: spi@f0000000 {
    status = "okay";
    cs-gpios = <&pioA 14 0>, <&pioA 7 0>, <0>, <0>;

    device@0 {
        compatible = "spidev";
        // spi-max-frequency = <50000000>;  // 50 MHz
        spi-max-frequency = <5000000>;      // 5 MHz
        reg = <0>;
    };

    device@1 {
        compatible = "spidev";
        // spi-max-frequency = <50000000>;  // 50 MHz
        spi-max-frequency = <5000000>;      // 5 MHz
        reg = <1>;
    };
};

in:

spi0: spi@f0000000 {
    status = "okay";
    cs-gpios = <&pioA 14 0>, <0>, <0>, <0>;

    device@0 {
        compatible = "spidev";
        // spi-max-frequency = <50000000>;  // 50 MHz
        spi-max-frequency = <5000000>;      // 5 MHz
        reg = <0>;
    };

};

In this way the PA7 pin is used for the /dev/ttyS3 instead of CS od SPI0.