设备树覆盖片段通知并加载子级两次

Question

我有以下设备树覆盖片段，加载时spidev会添加两次：

fragment@0 {
    target = <&fpga>;
    __overlay__ {
        #address-cells = <1>;
        #size-cells = <1>;

        spi2@600 {
            status = "okay";
            compatible = "opencores,spiocv2";
            #address-cells = <1>;
            #size-cells = <0>;
            reg = <0 0x800>;
            cell-index = <2>; // bus number

            spidev0 {
                 spi-max-frequency = <25000000>;
                 reg = <0>;
                 compatible = "spidev";
            };
        };
    };
};

1. 第一个通路of_overlay_create -> ... -> notifier_call_chain -> of_platform_notify -> ... -> device_attach -> ... -> spioc_driver_probe -> spi_register_master -> of_register_spi_devices -> of_register_spi_device -> spi_add_device
2. 然后再次通过of_overlay_create -> ... -> notifier_call_chain -> of_spi_notify -> of_register_spi_device -> spi_add_device

因为它首先正确加载，/dev/spidev2.0可用且工作正常，但第二次调用会导致丑陋的错误：

[    1.814623] opencores_spi 13e0000f3300000.spi2: chipselect 0 already in use
[    1.836491] spi_master spi2: spi_device register error /fpga/spi2@600/spidev0
[    1.857652] of_spi_notify: failed to create for '/fpga/spi2@600/spidev0'
[    1.877495] __of_changeset_entry_notify: notifier error @/fpga/spi2@600/spidev0

什么是防止重复加载的干净且正确的方法？或者如何阻止通知者通知平台和SPI？