[PATCH] staging: fbtft: avoid empty macro argument

[PATCH] staging: fbtft: avoid empty macro argument

[amanohina1]

Signed-off-by: amanohina1 <caiyuhe80@gmail.com>
---
 drivers/staging/fbtft/fbtft-bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
index 30e436ff19e4..d1eb3fc03d7a 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -62,9 +62,11 @@ out:									      \
 }                                                                             \
 EXPORT_SYMBOL(func);
 
-define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
+#define fbtft_nop(x) (x)
+
+define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, fbtft_nop)
 define_fbtft_write_reg(fbtft_write_reg16_bus8, __be16, u16, cpu_to_be16)
-define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, )
+define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, fbtft_nop)
 
 void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
 {
-- 
2.34.1

Re: [PATCH] staging: fbtft: avoid empty macro argument

[Andy Shevchenko]

On Sat, Mar 28, 2026 at 6:02 PM amanohina1 <caiyuhe80@gmail.com> wrote:

Read Submitting Patches documentation along with
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/tree/drivers/staging/fbtft/README?h=staging-next

Act accordingly.

-- 
With Best Regards,
Andy Shevchenko

Claude review: Re: [PATCH] staging: fbtft: avoid empty macro argument

[Claude Code Review Bot]

Overall Series Review

Subject: Re: [PATCH] staging: fbtft: avoid empty macro argument
Author: Andy Shevchenko <andy.shevchenko@gmail.com>
Patches: 2
Reviewed: 2026-03-31T17:56:51.241136

---

This is a single patch that replaces empty macro arguments in `define_fbtft_write_reg()` invocations with a no-op identity macro `fbtft_nop`. The change is functionally correct — the `modifier` parameter is used as `modifier(expr)` in the macro body, so passing an empty argument produces `((data_type)va_arg(...))` which works but relies on a GNU C extension (empty macro arguments are technically undefined behavior in ISO C, though widely tolerated). Replacing it with an explicit identity macro is cleaner.

However, the patch has issues that should be addressed before acceptance.

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Generated by Claude Code Patch Reviewer

Claude review: Re: [PATCH] staging: fbtft: avoid empty macro argument

[Claude Code Review Bot]

Patch Review

**Missing commit message body.** The patch has no description at all — just a Signed-off-by. It should explain *why* this change is being made (e.g., "Empty macro arguments are undefined behavior per ISO C99 §6.10.3 and trigger warnings with `-Wmissing-macro-arg`" or similar). A reviewer or future reader of `git log` needs to understand the motivation.

**The fix itself is correct.** The `modifier` parameter appears in three places in the macro body:

```c
buf[i] = modifier((data_type)va_arg(args, unsigned int));
*buf = modifier((data_type)va_arg(args, unsigned int));
*buf++ = modifier((data_type)va_arg(args, unsigned int));
```

Using `fbtft_nop(x)` defined as `(x)` correctly preserves the original semantics — it's an identity transformation, matching what the empty argument was implicitly doing.

**Naming/style nit:** The name `fbtft_nop` is slightly misleading — "nop" typically implies "no operation" (i.e., a statement with no effect), whereas this is an identity *function*. Something like `fbtft_identity` would be more descriptive, though this is minor and a matter of taste.

**Minor: `#define` placement is fine.** Placing the `#define` between the macro definition and its first use is reasonable. Since this is a file-scoped macro only used in this translation unit, it doesn't need to go in a header.

**Recommendation:** The patch needs a proper commit message. The code change itself is a reasonable cleanup. With a commit message added, this would be acceptable.

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Generated by Claude Code Patch Reviewer