Re: drivers/video/fbdev/au1100fb.c:448:46: error: implicit declaration of function 'KSEG1ADDR'; did you mean 'CKSEG1ADDR'?

[Helge Deller]

Hi Uwe,

On 3/5/26 09:07, Uwe Kleine-König wrote:
> On Wed, Mar 04, 2026 at 07:23:30PM +0100, Helge Deller wrote:
> > * kernel test robot <lkp@xxxxxxxxx>:
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head:   0031c06807cfa8aa51a759ff8aa09e1aa48149af
> > > commit: 6f366e86481a7503a821de82930df517dddd4047 fbdev: au1100fb: Make driver compilable on non-mips platforms
> > > date:   13 days ago
> > > config: mips-randconfig-r052-20260304 (https://download.01.org/0day-ci/archive/20260304/202603042127.PT6LuKqi-lkp@xxxxxxxxx/config)
> > > compiler: mips64-linux-gcc (GCC) 14.3.0
> > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260304/202603042127.PT6LuKqi-lkp@xxxxxxxxx/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@xxxxxxxxx>
> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202603042127.PT6LuKqi-lkp@xxxxxxxxx/
> > >
> > > All error/warnings (new ones prefixed by >>):
> > >
> > >     drivers/video/fbdev/au1100fb.c: In function 'au1100fb_drv_probe':
> > > > > drivers/video/fbdev/au1100fb.c:448:46: error: implicit declaration of function 'KSEG1ADDR'; did you mean 'CKSEG1ADDR'? [-Wimplicit-function-declaration]
> > >       448 |         fbdev->regs = (struct au1100fb_regs*)KSEG1ADDR(fbdev->info.fix.mmio_start);
> > >           |                                              ^~~~~~~~~
> > >           |                                              CKSEG1ADDR
> > > > > drivers/video/fbdev/au1100fb.c:448:23: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
> > >       448 |         fbdev->regs = (struct au1100fb_regs*)KSEG1ADDR(fbdev->info.fix.mmio_start);
> > >           |                       ^
> >
> > I've pushed the patch below into the fbdev git tree.
> > It should (hopefully) fix the issue.
> >
> > Helge
> >
> >
> > From: Helge Deller <deller@xxxxxx>
> > Subject: [PATCH] fbdev: au1100fb: Fix build on MIPS64
> >
> > Fix an error reported by the kernel test robot:
> >   au1100fb.c: error: implicit declaration of function 'KSEG1ADDR'; did you mean 'CKSEG1ADDR'?
> >
> > The header asm/mach-au1x00/au1000.h is unused apart from pulling in
> > <linux/delay.h> (for mdelay()) and <linux/io.h> (for KSEG1ADDR()). Then
> > the only platform specific part in the driver is the usage of the KSEG1ADDR
> > macro, which for the non-mips case can be stubbed.
>
> This paragraph is copied from 6f366e86481a and doesn't make sense here.

Yes, I noticed that later and removed it already.

> I'd write something like:
>
> 	arch/mips/include/asm/addrspace.h defines KSEG1ADDR only for 32 bit
> 	configurations. So provide its compile-test stub also for 64bit
> 	mips builds.

Ok, added.

> > Fixes: 6f366e86481a ("fbdev: au1100fb: Make driver compilable on non-mips platforms")
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202603042127.PT6LuKqi-lkp@xxxxxxxxx/
> > Signed-off-by: Helge Deller <deller@xxxxxx>
> > Cc: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx>
> >
> > diff --git a/drivers/video/fbdev/au1100fb.c b/drivers/video/fbdev/au1100fb.c
> > index 1a04154bc535..3b104d377d28 100644
> > --- a/drivers/video/fbdev/au1100fb.c
> > +++ b/drivers/video/fbdev/au1100fb.c
> > @@ -380,7 +380,7 @@ static struct au1100fb_panel known_lcd_panels[] =
> >   #define panel_is_color(panel) (panel->control_base & LCD_CONTROL_PC)
> >   #define panel_swap_rgb(panel) (panel->control_base & LCD_CONTROL_CCO)
> >   
> > -#if defined(CONFIG_COMPILE_TEST) && !defined(CONFIG_MIPS)
> > +#if defined(CONFIG_COMPILE_TEST) && !(defined(CONFIG_MIPS) && !defined(CONFIG_64BIT))
>
> The condition is equivalent to
>
> 	defined(CONFIG_COMPILE_TEST) && (!defined(CONFIG_MIPS) || defined(CONFIG_64BIT))
>
> which is logically a bit easier, but I'm unsure if it's easier to
> understand (IMHO both are bad).

Yes, both are bad. I changed it to your proposal.
 
> >   /* This is only defined to be able to compile this driver on non-mips platforms */
>
> Maybe adapt the comment here, too? Something like:
>
> 	/*
> 	 * KSEG1ADDR() is defined in arch/mips/include/asm/addrspace.h
> 	 * for 32 bit configurations. Provide a stub for compile testing
> 	 * on other platforms.
> 	 */

done.

I've updated the patch in the fbdev git tree, which you can find here:
https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/log/?h=for-next

I'll keep the patch a few days in there and will push next week.

Helge