I am interfacing display with MIPI interface with linux board. Display requires 3 lane MIPI so I went with intermediate converter from RGB to MIPI. It appeared that there are not many CPUs with 3-4 MIPI and those who have may lack corresponding driver support. As a target CPU I am using Allwinner R8 with RGB controller.

As far as I understand, I need to write frambuffer driver which communicates via SSD2828 via SPI interface. Several questions:
1) There are many FB driver examples. But are there FB examples which incorporates SPI?
2) Does this driver should also configure display TFT controller (ILI9881C) or configuring SSD2828 will be enough?

You just have to interface with the SSD2828. You should view the kernel code for the spi module to check how to do it.

Thanks, I've got a point.