Camera Input on Zybo-Z20 Petalinux

[joeyh021]

We have set up the Petalinux demo for the Zybo-Z20 board(https://digilent.com/reference/programmable-logic/zybo-z7/demos/petalinux) , and have the webcam input working (and using v4l2-ctl and ffmpeg to stream over the network).

We'd like to play around with applying some image processing filters in hardware by adding some extra modules in the camera's input datapath, but we're stuck on exactly how to do so.

Currently the input video data goes to the MIPI interface subsystem, then from there into a framebuffer via AXI-Stream. We tried modifying the block design so that the datapath was something like

MIPI interface --> axi-stream to video out -> image filter -> video in to axi stream -> framebuffer, and using a video timing geneartor IP to generate hsync/vsync signals for the filter, but this just resulted in the camera not being recognised on boot.

What would be the best way to go about adding a filter to the camera input in hardware using this project as a base?

Thanks in advance, help is really appreciated!

[Ionel]

On the Linux side after adding extra filters no changes should be done after Importing the new hardware (petalinux-config --get-hw-description=<path-to-xsa>)
The exception is if the filter needs driving in which case:

1. Add device tree node(s) for the filter(s)
2. Add a kernel driver (see Linux Media Subsystem)
3. Add some user-space app to use the driver if necessary.

Quote

but this just resulted in the camera not being recognised on boot.

What lead to this conclusion?