spacemit: rtl8852bs: guard GCC-only warning flags for clang builds

[iav]

Description

The rtl8852bs driver bundled in the spacemit vendor kernel adds two GCC-only warning options unconditionally in its Makefile:

ccflags-y += -Wno-restrict
ccflags-y += -Wno-old-style-declaration

clang does not know these options, and with the kernel's -Werror=unknown-warning-option the build fails:

error: unknown warning option '-Wno-restrict' [-Werror,-Wunknown-warning-option]
error: unknown warning option '-Wno-old-style-declaration'

On the spacemit family the driver is in-tree and EXTRAWIFI is forced off in the family config, so it cannot be excluded — this breaks every clang kernel build for the family.

Fix: wrap the two GCC-only flags in $(call cc-disable-warning, ...), so each is added only for a compiler that understands the positive warning name (GCC). This is also robust against CC carrying a ccache prefix, unlike the ifeq ($(CC), clang) compare further down the same Makefile. The remaining -Wno-* in that block (unused, empty-body, missing-prototypes, missing-declarations) are understood by clang and left untouched. GCC behaviour is unchanged.

How Has This Been Tested?

Kernel build for bananapif3 (spacemit, kernel 6.18):

• GCC full build: rtl8852bs (372 objects) + 8852bs.ko + linux-image .deb — 0 errors.
• clang full build with the driver enabled: 8852bs.ko built under clang, 0 unknown-warning-option / 0 errors, linux-image .deb produced.

Repro:

./compile.sh kernel BOARD=bananapif3 BRANCH=current KERNEL_COMPILER=clang

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings

Summary by CodeRabbit

• Bug Fixes
  • Improved wireless driver build compatibility by avoiding compiler flags that can break clang-based builds.
  • Reduced build failures caused by unsupported warning options while keeping GCC-compatible warning handling intact.

[coderabbitai]

📝 Walkthrough

Walkthrough

This change modifies a kernel patch file for the rtl8852bs wireless driver Makefile, converting unconditional GCC-only warning suppression flags (-Wno-restrict, -Wno-old-style-declaration) into conditional flags using cc-disable-warning, avoiding build failures on clang.

Changes

rtl8852bs Patch Update

Layer / File(s)	Summary
Conditional warning suppression patch/kernel/archive/spacemit-6.18/020-rtl8852bs-guard-gcc-only-warnings-for-clang.patch	Replaces unconditional `-Wno-restrict` and `-Wno-old-style-declaration` flags with `$(call cc-disable-warning, ...)` equivalents so they only apply when the compiler supports them.

Estimated code review effort: 1 (Trivial) | ~3 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: guarding GCC-only warning flags for clang builds in rtl8852bs.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

✅ This PR has been reviewed and approved — all set for merge!