firefly@firefly:~$ dmesg | grep spi
[ 1.278569] rockchip-spi ff1c0000.spi: Failed to request TX DMA channel
[ 1.279170] rockchip-spi ff1c0000.spi: Failed to request RX DMA channel
[ 1.279755] rockchip-spi ff1c0000.spi: no high_speed pinctrl state
[ 1.281334] register spi return v = :0
[ 1.282417] rockchip-pinctrl pinctrl: pin gpio3-7 already requested by ff1c0000.spi; cannot claim for fe300000.ethernet
firefly@firefly:~$ sudo ./a.out -D /dev/spidev0.0 -s 200000 spi mode: 0x0
bits per word: 8
max speed: 200000 Hz (200 KHz)
333333
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF | …