[PATCH] staging: fbtft: fix coding style issue in fbtft-bus.c

[PATCH] staging: fbtft: fix coding style issue in fbtft-bus.c

[Baker]

Remove trailing space and comma before closing parenthesis ')' in
define_fbtft_write_reg macro as reported by checkpatch.pl.

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

diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
index 30e436ff19e4..409770891c54 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -62,9 +62,9 @@ out:									      \
 }                                                                             \
 EXPORT_SYMBOL(func);
 
-define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
+define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
 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)
 
 void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
 {
-- 
2.47.3

[PATCH v3] staging: fbtft: replace empty macro args with identity converter

[Baker]

The define_fbtft_write_reg macro calls 'modifier' as a function.
Passing an empty token as modifier is undefined behavior in C for
fixed-arity macros. Introduce fbtft_no_conv() as an identity
function to replace the empty args in the no-conversion cases.

Signed-off-by: Baker <mzndmzn@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..7f3fd30576ab 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -11,6 +11,8 @@
  *
  *****************************************************************************/
 
+#define fbtft_no_conv(x) (x)
+
 #define define_fbtft_write_reg(func, buffer_type, data_type, modifier)        \
 void func(struct fbtft_par *par, int len, ...)                                \
 {                                                                             \
@@ -62,9 +64,9 @@ out:									      \
 }                                                                             \
 EXPORT_SYMBOL(func);
 
-define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
+define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, fbtft_no_conv)
 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_no_conv)
 
 void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
 {
-- 
2.47.3

Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter

[Andy Shevchenko]

On Sun, Apr 12, 2026 at 8:33 PM Baker <mzndmzn@gmail.com> wrote:
>
> The define_fbtft_write_reg macro calls 'modifier' as a function.
> Passing an empty token as modifier is undefined behavior in C for
> fixed-arity macros. Introduce fbtft_no_conv() as an identity
> function to replace the empty args in the no-conversion cases.

This trick is used in the kernel (usually for u8). If you really want
to improve, use _Generic() instead.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter

[Greg KH]

On Mon, Apr 13, 2026 at 08:58:50AM +0300, Andy Shevchenko wrote:
> On Sun, Apr 12, 2026 at 8:33 PM Baker <mzndmzn@gmail.com> wrote:
> >
> > The define_fbtft_write_reg macro calls 'modifier' as a function.
> > Passing an empty token as modifier is undefined behavior in C for
> > fixed-arity macros. Introduce fbtft_no_conv() as an identity
> > function to replace the empty args in the no-conversion cases.
> 
> This trick is used in the kernel (usually for u8). If you really want
> to improve, use _Generic() instead.

No, sorry, this code is fine as-is.

greg k-h

Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter

[Andy Shevchenko]

On Mon, Apr 13, 2026 at 9:03 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> On Mon, Apr 13, 2026 at 08:58:50AM +0300, Andy Shevchenko wrote:
> > On Sun, Apr 12, 2026 at 8:33 PM Baker <mzndmzn@gmail.com> wrote:
> > >
> > > The define_fbtft_write_reg macro calls 'modifier' as a function.
> > > Passing an empty token as modifier is undefined behavior in C for
> > > fixed-arity macros. Introduce fbtft_no_conv() as an identity
> > > function to replace the empty args in the no-conversion cases.
> >
> > This trick is used in the kernel (usually for u8). If you really want
> > to improve, use _Generic() instead.
>
> No, sorry, this code is fine as-is.

Works for me. I suggested they explore the possibilities, it might be
helpful somewhere else in case of the similar requirements (like in a
new code).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3] staging: fbtft: replace empty macro args with identity converter

[Greg KH]

On Sun, Apr 12, 2026 at 12:33:17PM -0500, Baker wrote:
> The define_fbtft_write_reg macro calls 'modifier' as a function.
> Passing an empty token as modifier is undefined behavior in C for
> fixed-arity macros. Introduce fbtft_no_conv() as an identity
> function to replace the empty args in the no-conversion cases.
> 
> Signed-off-by: Baker <mzndmzn@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..7f3fd30576ab 100644
> --- a/drivers/staging/fbtft/fbtft-bus.c
> +++ b/drivers/staging/fbtft/fbtft-bus.c
> @@ -11,6 +11,8 @@
>   *
>   *****************************************************************************/
>  
> +#define fbtft_no_conv(x) (x)
> +
>  #define define_fbtft_write_reg(func, buffer_type, data_type, modifier)        \
>  void func(struct fbtft_par *par, int len, ...)                                \
>  {                                                                             \
> @@ -62,9 +64,9 @@ out:									      \
>  }                                                                             \
>  EXPORT_SYMBOL(func);
>  
> -define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
> +define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, fbtft_no_conv)
>  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_no_conv)
>  
>  void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
>  {
> -- 
> 2.47.3
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- It looks like you did not use your "real" name for the patch on either
  the Signed-off-by: line, or the From: line (both of which have to
  match).  Please read the kernel file,
  Documentation/process/submitting-patches.rst for how to do this
  correctly.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH] staging: fbtft: fix coding style issue in fbtft-bus.c

[kernel test robot]

Hi Baker,

kernel test robot noticed the following build errors:

[auto build test ERROR on staging/staging-testing]

url:    https://github.com/intel-lab-lkp/linux/commits/Baker/staging-fbtft-fix-coding-style-issue-in-fbtft-bus-c/20260414-101811
base:   staging/staging-testing
patch link:    https://lore.kernel.org/r/20260412173317.3329-1-mzndmzn%40gmail.com
patch subject: [PATCH] staging: fbtft: fix coding style issue in fbtft-bus.c
config: arm-randconfig-r072-20260414 (https://download.01.org/0day-ci/archive/20260414/202604141939.LhzKrfey-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 13.4.0
smatch: v0.5.0-9007-gcf3ea02b
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260414/202604141939.LhzKrfey-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202604141939.LhzKrfey-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/staging/fbtft/fbtft-bus.c:65:53: error: macro "define_fbtft_write_reg" requires 4 arguments, but only 3 given
      65 | define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
         |                                                     ^
   drivers/staging/fbtft/fbtft-bus.c:14: note: macro "define_fbtft_write_reg" defined here
      14 | #define define_fbtft_write_reg(func, buffer_type, data_type, modifier)        \
         | 
>> drivers/staging/fbtft/fbtft-bus.c:65:23: error: expected ';' before 'void'
      65 | define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
         |                       ^
         |                       ;
   drivers/staging/fbtft/fbtft-bus.c:67:57: error: macro "define_fbtft_write_reg" requires 4 arguments, but only 3 given
      67 | define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16)
         |                                                         ^
   drivers/staging/fbtft/fbtft-bus.c:14: note: macro "define_fbtft_write_reg" defined here
      14 | #define define_fbtft_write_reg(func, buffer_type, data_type, modifier)        \
         | 
   drivers/staging/fbtft/fbtft-bus.c:67:23: error: expected ';' before 'void'
      67 | define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16)
         |                       ^
         |                       ;
      68 | 
      69 | void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
         | ~~~~                   


vim +/define_fbtft_write_reg +65 drivers/staging/fbtft/fbtft-bus.c

    64	
  > 65	define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8)
    66	define_fbtft_write_reg(fbtft_write_reg16_bus8, __be16, u16, cpu_to_be16)
    67	define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16)
    68	

-- 
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