[Cin] OpenCL again

So, I run veeery experimental clvk (OpenCL via Vulkan) on my termux, ffmpeg tried to init filter but died. I guess my day is not today ... Anyway, my test line was: ffmpeg -init_hw_device opencl=gpu -filter_hw_device gpu -i ~/20210419_055507A.mp4 -vf "hwupload, boxblur_opencl, hwdownload,format=yuv420p" -f null /dev/null for different filters format might be yuv420p or nv12 ... I wonder if anyone here have working OpenCL ffmpeg setup ? I'll try with llvmpipe/rusticl on desktop .... but it guaranteed to be slow.