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Awesome! I think the next step for this project would be to implement a proper DRM kernel driver and device tree overlay, instead of copying the framebuffer in
by mafuyu 2y ago
Awesome! I think the next step for this project would be to implement a proper DRM kernel driver and device tree overlay, instead of copying the framebuffer in userspace.
For reference, take a look at the Beepy display driver module: https://github.com/ardangelo/sharp-drm-driver https://github.com/ardangelo/sharp-drm-driver. It's for a monochrome Sharp memory LCD, but still uses the SPI interface on a RasPi.
- nomza 2y agoThanks for the suggestion! I have no idea about drivers, so it would be great for learning. Pardon my ignorance, but can the gpu render to other display devices as normal?
- sjuut 2y agoI see there is an upstream tiny-DRM based kernel driver for ST7735r, which might be compatible with your ST7789, or might require some (hopefully) minimal adjustments: https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/tiny/st7735r.c https://elixir.bootlin.com/linux/latest/source/drivers/gpu/d...
- mafuyu 2y ago> can the gpu render to other display devices as normal? Yep, it will just result in your driver showing up as another `fb` device. Then, you can configure the kernel fbcon boot parameter to use your display for tty, or launch X configured to use your fb device. This would also let you do fun stuff like run mpv pointed directly at the fb device without running X at all :) I put my email in my profile, so feel free to message me if you need any pointers.