riscv/bl602: Enable SPI Master in SPI Poll Send

[lupyuen]

Summary

SPI Poll Send bl602_spi_poll_send() doesn't send any SPI Data because it doesn't enable SPI Master and it doesn't clear the SPI FIFO. Also it hangs because it loops forever waiting for the FIFO.

We fix this problem by moving the code that enables SPI Master and clears the FIFO, from SPI Poll Exchange bl602_spi_poll_exchange() to SPI Poll Send. (Note that SPI Poll Exchange calls SPI Poll Send)

More Details Here

Impact

This problem affects all NuttX Drivers that call SPI_SEND() on BL602, including the ST7789 Display Driver.

Previously SPI_SEND() didn't send any SPI Data and never returns, because it loops forever waiting to receive data.

Now SPI_SEND() sends data and returns correctly.

More Details Here

Testing

We tested the modified SPI Poll Send with NuttX ST7789 Driver and a Logic Analyser on PineCone BL602:

• Testing with Logic Analyser

We also tested LVGL with ST7789 on PineCone BL602:

• Testing with LVGL

As for the modified SPI Poll Exchange, we tested with Semtech SX1262 SPI Transceiver on PineCone BL602:

• Testing SPI Poll Exchange