Hi Greg and Sasha,
Please find attached backports for commit feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS") and its dependent changes, commit d5c8d6e0fa61 ("kbuild: Update assembler calls to use proper flags and language target") and its dependent changes, and commit 7db038d9790e ("drm/amd/display: Do not add '-mhard-float' to dml_ccflags for clang") for 6.1 and earlier. The second listed change is already in 6.1 so that series is a little shorter.
These changes are needed there due to an upstream LLVM change [1] that changes the behavior of -Qunused-arguments with unknown target options, which is only used in 6.1 and older since I removed it in commit 8d9acfce3332 ("kbuild: Stop using '-Qunused-arguments' with clang") in 6.3.
Please let me know if there are any issues, I will try to pay attention for any issues that crop up in the stable review period from these changes but please ping me if you remember.
Cheers, Nathan
[1]: https://github.com/llvm/llvm-project/commit/a4b2f4a72aa9b4655ecc723838830e0a...