I've bought a 4 inch Waveshare Spotpear LCD screen (This one) and with the help from How to install Waveshare SpotPear 4 inch LCD in RaspberryPI 2? I've managed to get it mostly working.
The problem I'm having now is that I was hoping to use the screen for a handheld console project using RetroPi (ala Adafruit's PiGRRL).
I'm using the framebuffer copy workaround to allow Emulationstation/RetroPie to display on the screen (since it works over GPIO and not HDMI) but I can't seem to get the performance/stability right.
With the default fbtft_device speed of 16000000 in /etc/modules it runs terribly slow. However raising this value to >24000000 results in a pretty smooth framerate but terribly unstable visuals (screen spots, crazy colours all the usual things you might see if it was a PC GPU overheating). Is it maybe a power issue?
Has anyone managed to get this display to work with RetroPi? It looks like its 3.5 inch smaller brother would probably manage better with higher default device speeds? If I went with a larger 5 inch screen and HDMI would I have a better time of it (by not needing to copy the frame buffer?)
Does anyone have any advice on increasing fbcp's performance or increasing stability at higher display device speeds? (what does that speed value actually represent?)