Almost all smartphones on the market seem to use a distinct LCD as their display, though most use an ARM processor with a GPU from one of a relatively (compared to the screens) small number of companies (PowerVR from Imagination, Mali, Adreno from Qualcomm, etc). When a company goes about designing a smartphone, I assume their choice of LCD isn't restricted by their choice of SoC (and therefore GPU).
So, once they have chosen their SoC, how do they interface their LCD and GPU? Is there a standard protocol? They don't use HDMI under the hood, so what is it? If they wanted to take for example this display(chosen for no particular reason) and use this driver (purely based on recommendation by aforementioned display), where would they start? Is engineering an interface a whole difficult task by itself?
I have seen a few different interfaces mentioned while researching this before, for example:
- SPI - this isn't fast enough to drive 1080p@60, which many smartphones provide
- i80 - this doesn't provide 8 bits per colour as far as I can tell, but moreover I can't find a "standard" description of this interface
- various parallel rgb interfaces which aren't very well documented.
I feel as though this gap in my understanding in part comes from incomplete datasheets, Chinese datasheets I can't understand or datasheets behind paywalls. How can I gain more understanding on this topic? Or do I need to be "in the business" to even start?
Any advice or guidance for further understanding is appreciated.