[BeagleBoneAI]i use spidev1.0 or spidev1.0, but application can not communicate to spi slave for BeagleBoneAI

I am creating an application using /dev/spidev1.0 /dev/spidev1.1.
However, the signals such as spi clcok, MISO, MOSI, and SPI_CS are not high/low, regardless of what is used.

For the BeagleBone AI
P9.28 -SPI3_SS1
P9.29 -SPI3_MISO
P9.31 SPI3_SCK

Why can’t I do SPI communication with the slave?

Of course, /dev/spidev1.0 and /dev/spi1.1 were created normally by configuring the devicetree.