https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942561

There are still many mips{,64} machines without MSA support.
Unconditionally enabling MSA by default will lead to SIGILL in most cases.

https://github.com/opencv/opencv/blob/4.1.2/cmake/OpenCVCompilerOptimizations.cmake#L345-L349

System information (version)

opencv: 4.1.2