TMS320F28388D: SPI configure

Hello：

Why does the SPI configure all pins to pull up when configuring SPI pin parameters?

Does the pull up here make sense? I have tried to configure the clock pin and MOSI pin as push-pull ，then， the MISO pin as floating air input, and the SPI also works fine

thanks

path：

C:\ti\c2000\C2000Ware_3_03_00_00\driverlib\f2838x\examples\c28x\spi

“spi_ex6_eeprom “，and “spi_ex5_external_loopback”

   // GPIO16 is the SPISIMOA   pin.
    //
    GPIO_setMasterCore(16, GPIO_CORE_CPU1);
    GPIO_setPinConfig(GPIO_16_SPIA_SIMO);
    GPIO_setPadConfig(16, GPIO_PIN_TYPE_PULLUP);
    GPIO_setQualificationMode(16, GPIO_QUAL_ASYNC);

    //
    // GPIO17 is the SPISOMIA.
    //
    GPIO_setMasterCore(17, GPIO_CORE_CPU1);
    GPIO_setPinConfig(GPIO_17_SPIA_SOMI);
    GPIO_setPadConfig(17, GPIO_PIN_TYPE_PULLUP);
    GPIO_setQualificationMode(17, GPIO_QUAL_ASYNC);
    
    //
    // GPIO18 is the SPICLKA.
    //
    GPIO_setMasterCore(18, GPIO_CORE_CPU1);
    GPIO_setPinConfig(GPIO_18_SPIA_CLK);
    GPIO_setPadConfig(18, GPIO_PIN_TYPE_PULLUP);