Looking at the ESPHome source code, I’m starting to think that defining a new “Octal” SPI type would be the easiest, similar to the Quad SPI. It would allow using the ILI9xxx-ST7789V display driver as-is.
The “problem” is that the 8-bit parallel interface on the ST7789V uses rising edges on WRX and RDX to perform write and read operations via shared data bits whereas SPI uses a rising edge on SCK with parallel write and read operations on MOSI and MISO – so it is not “SPI”. Would the ESP powers that be (@clydebarrow) allow such an overloading of the SPI component in an eventual contribution?
Looking at the ILI9XXX driver, it always transmits bytes. So the proper solution would be for it to be implemented on top of a “byte Tx/Rx” component, SPI being one possible implementation. But that would be a LOT more work and maybe not backward compatible.
Thoughts?