Re: [PATCH] serial: pic32: Fix build warning when CONFIG_OF is disabled

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jan 27, 2025 at 04:29:24PM +0800, Yu-Chun Lin wrote:
> On Sun, Jan 26, 2025 at 08:30:33PM +0100, Greg KH wrote:
> > On Mon, Jan 27, 2025 at 12:31:15AM +0800, Yu-Chun Lin wrote:
> > > As reported by the kernel test robot, the following warning occurs:
> > > 
> > > >> drivers/tty/serial/pic32_uart.c:904:34: warning: 'pic32_serial_dt_ids' defined but not used [-Wunused-const-variable=]
> > >      904 | static const struct of_device_id pic32_serial_dt_ids[] = {
> > >          |                                  ^~~~~~~~~~~~~~~~~~~
> > > 
> > > The 'pic32_serial_dt_ids' array is only used when CONFIG_OF is enabled.
> > > Wrapping its definition and 'MODULE_DEVICE_TABLE' in '#ifdef CONFIG_OF'
> > > prevents a compiler warning when OF is disabled.
> > > 
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Closes: https://lore.kernel.org/oe-kbuild-all/202501260006.ecUsBidz-lkp@intel.com/
> > > Signed-off-by: Yu-Chun Lin <eleanor15x@gmail.com>
> > > ---
> > >  drivers/tty/serial/pic32_uart.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
> > > index 14d50bd7f1bd..a228a55102c6 100644
> > > --- a/drivers/tty/serial/pic32_uart.c
> > > +++ b/drivers/tty/serial/pic32_uart.c
> > > @@ -948,11 +948,13 @@ static void pic32_uart_remove(struct platform_device *pdev)
> > >  	pic32_sports[sport->idx] = NULL;
> > >  }
> > >  
> > > +#ifdef CONFIG_OF
> > >  static const struct of_device_id pic32_serial_dt_ids[] = {
> > >  	{ .compatible = "microchip,pic32mzda-uart" },
> > >  	{ /* sentinel */ }
> > >  };
> > >  MODULE_DEVICE_TABLE(of, pic32_serial_dt_ids);
> > > +#endif
> > 
> > That should not be needed, no other bus requires this, please fix up the
> > use of the OF macros instead.
> 
> So I should remove of_match_ptr and add the CONFIG_OF as a dependency
> for the configuration. Correct?

I don't know, but putting #ifdef in .c files is not the correct solution
at all.

thanks,

greg k-h