Klipper Setup w/ KlipperScreen

I reflashed my RPi Zero 2 W with a stock Debian install and started installing Klipper-for-CNC with Kiauh. That was simple enough but I also wanted to get KlipperScreen working with a 3.5” capacitive touchscreen I had lying around.

KlipperScreen outputs video to the Linux framebuffer with X11 but without HDMI this wasn’t visible. I’m using an ST7796 display over SPI. After connecting the screen to GPIO, I thought an easy to use driver would already exist for this display. There was this one which I tried setting up. Unfortunately this a) didn’t support the RPi Zero 2 W, but that was easy to fix and b) relied on the old VideoCore framework which Raspberry Pi OS doesn’t ship with anymore.
After that, I went digging for another solution. I found this repo and this forum post which showed that the kernel already had support for generic displays like these, so I just had to add the init sequence of bytes for my display. After hours of tweaking with boot settings I finally got it working!
Now I needed touch to work, which used an FT6336U driver. At the bottom of some forum post I was able to find a repo which had drivers for the OrangePi for my exact screen. This probably would’ve been helpful getting the screen working but I anyways like my solution better. I compiled the driver in the repo and remade the DTS file for an RPi Zero 2 W rather than an Orange Pi. Surprisingly, this just worked! The touch coordinate orientation was correct, and even gestures like scrolling worked perfectly!

Now I have Klipper fully setup with my display and need to connect it to my motherboard.