ISP downscaling not working after Oct 2022 firmware

[tmm1]

I'm using ISP to upload and downscale yuv420p images, using https://patchwork.ffmpeg.org/project/ffmpeg/patch/[email protected]/

After https://github.com/raspberrypi/firmware/commit/bfbd42ef2c93eb4c4b688759a9c879423b479448 ("firmware: isp: Run ISP without hi-res output buffer"), this is no longer working

I confirmed that the firmware release before that commit still works. After that commit, I keep feeding in data to the ISP and get no output.

According to @6by9:

Libcamera wants to be able to generate stats without generating output pixels. It should really be checking that at least one output is active before doing anything, but I suspect it isn't and therefore you don't get the 1 in 1 out behaviour you're expecting.

[tmm1]

@6by9 @popcornmix is there anything I can do to help fix this regression?