On Tue, Jun 11, 2019 at 10:25:28AM +1000, Stephen Rothwell wrote:
> Hi Wolfram,
> 
> After merging the i2c tree, today's linux-next build (x86_64 allmodconfig)
> produced this warning:
> 
> drivers/media/dvb-frontends/tua6100.c: In function 'tua6100_set_params':
> drivers/media/dvb-frontends/tua6100.c:71: warning: "_P" redefined
>  #define _P 32
>  
> In file included from include/acpi/platform/aclinux.h:54,
>                  from include/acpi/platform/acenv.h:152,
>                  from include/acpi/acpi.h:22,
>                  from include/linux/acpi.h:21,
>                  from include/linux/i2c.h:17,
>                  from drivers/media/dvb-frontends/tua6100.h:22,
>                  from drivers/media/dvb-frontends/tua6100.c:24:
> include/linux/ctype.h:14: note: this is the location of the previous definition
>  #define _P 0x10 /* punct */
> 
> Exposed by commit
> 
>   5213d7efc8ec ("i2c: acpi: export i2c_acpi_find_adapter_by_handle")
> 
> Since that included <linux/acpi.h> from <linux/i2c.h>
> 
> Originally introduced by commit
> 
>   00be2e7c6415 ("V4L/DVB (4606): Add driver for TUA6100")
> 
> The _P in <linux/ctype.h> has existed since before git.

I suggest to fix the driver by adding a TUA6100_ prefix to the defines.
I can cook up a patch for that.