diff mbox series

staging: sm750: Fix missing config in Kconfig

Message ID 20240921180612.57657-2-fgasperin@lkcamp.dev
State New
Headers show
Series staging: sm750: Fix missing config in Kconfig | expand

Commit Message

Fabricio Gasperin Sept. 21, 2024, 6:06 p.m. UTC 
Fixes the following compilation error:

ERROR: modpost: "fb_io_read" [drivers/staging/sm750fb/sm750fb.ko] undefined!
ERROR: modpost: "fb_io_write" [drivers/staging/sm750fb/sm750fb.ko] undefined!
ERROR: modpost: "fb_io_mmap" [drivers/staging/sm750fb/sm750fb.ko] undefined!

Signed-off-by: Fabricio Gasperin <fgasperin@lkcamp.dev>
---
 drivers/staging/sm750fb/Kconfig | 1 +
 1 file changed, 1 insertion(+)

Comments

gregkh@linuxfoundation.org Oct. 9, 2024, 9:56 a.m. UTC | #1 
On Sat, Sep 21, 2024 at 03:06:09PM -0300, Fabricio Gasperin wrote:
> Fixes the following compilation error:
> 
> ERROR: modpost: "fb_io_read" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> ERROR: modpost: "fb_io_write" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> ERROR: modpost: "fb_io_mmap" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> 
> Signed-off-by: Fabricio Gasperin <fgasperin@lkcamp.dev>
> ---
>  drivers/staging/sm750fb/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/staging/sm750fb/Kconfig b/drivers/staging/sm750fb/Kconfig
> index 08bcccdd0f1c..eca1aa43d725 100644
> --- a/drivers/staging/sm750fb/Kconfig
> +++ b/drivers/staging/sm750fb/Kconfig
> @@ -3,6 +3,7 @@ config FB_SM750
>  	tristate "Silicon Motion SM750 framebuffer support"
>  	depends on FB && PCI && HAS_IOPORT
>  	select FB_MODE_HELPERS
> +	select FB_IOMEM_FOPS
>  	select FB_CFB_FILLRECT
>  	select FB_CFB_COPYAREA
>  	select FB_CFB_IMAGEBLIT
> -- 
> 2.46.1
> 
> 

What is causing this error?  What commit created the problem, and why
has no one reported it yet?

confused,

greg k-h
Vinicius Peixoto Oct. 9, 2024, 1:44 p.m. UTC | #2 
Hi Greg,

On 10/9/24 06:56, Greg Kroah-Hartman wrote:
> On Sat, Sep 21, 2024 at 03:06:09PM -0300, Fabricio Gasperin wrote:
>> Fixes the following compilation error:
>>
>> ERROR: modpost: "fb_io_read" [drivers/staging/sm750fb/sm750fb.ko] undefined!
>> ERROR: modpost: "fb_io_write" [drivers/staging/sm750fb/sm750fb.ko] undefined!
>> ERROR: modpost: "fb_io_mmap" [drivers/staging/sm750fb/sm750fb.ko] undefined!
>>
>> Signed-off-by: Fabricio Gasperin <fgasperin@lkcamp.dev>
>> ---
>>   drivers/staging/sm750fb/Kconfig | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/staging/sm750fb/Kconfig b/drivers/staging/sm750fb/Kconfig
>> index 08bcccdd0f1c..eca1aa43d725 100644
>> --- a/drivers/staging/sm750fb/Kconfig
>> +++ b/drivers/staging/sm750fb/Kconfig
>> @@ -3,6 +3,7 @@ config FB_SM750
>>   	tristate "Silicon Motion SM750 framebuffer support"
>>   	depends on FB && PCI && HAS_IOPORT
>>   	select FB_MODE_HELPERS
>> +	select FB_IOMEM_FOPS
>>   	select FB_CFB_FILLRECT
>>   	select FB_CFB_COPYAREA
>>   	select FB_CFB_IMAGEBLIT
>> -- 
>> 2.46.1
>>
>>
> 
> What is causing this error? What commit created the problem, and why
> has no one reported it yet?

This happens because drivers/staging/sm750fb/sm750.c, defines an fb_ops 
structure:

static const struct fb_ops lynxfb_ops = {
	.owner = THIS_MODULE,
	FB_DEFAULT_IOMEM_OPS,
	...
};

FB_DEFAULT_IOMEM_OPS expands to the fb_io_* helpers declared in 
include/linux/fb.h and defined in drivers/video/fbdev/core/fb_io_fops.c; 
however, the latter is gated by FB_IOMEM_FOPS, so when compiling a 
kernel with CONFIG_STAGING=y + CONFIG_FB=m + CONFIG_FB_SM750=m, you get 
the following error:

ERROR: modpost: "fb_io_read" [drivers/staging/sm750fb/sm750fb.ko] undefined!
ERROR: modpost: "fb_io_write" [drivers/staging/sm750fb/sm750fb.ko] 
undefined!
ERROR: modpost: "fb_io_mmap" [drivers/staging/sm750fb/sm750fb.ko] undefined!
make[2]: *** [scripts/Makefile.modpost:145: Module.symvers] Error 1

So in order to solve it we select FB_IOMEM_FOPS, much like the other 
FB_* drivers do in drivers/video/fbdev/Kconfig.

Not entirely sure why this wasn't caught before, but the commit that 
broke the build for sm750fb is 6b180f66c0dd ("fbdev: Provide I/O-memory 
helpers as module"), which made the fb_io_* helpers be built as a 
separate module instead of being bundled in fb.o (which is what sm750fb 
was relying on). I think Fabricio can add a "Fixes:" tag in v2.

Thanks,
Vinicius

> 
> confused,
> 
> greg k-h
gregkh@linuxfoundation.org Oct. 10, 2024, 9:41 a.m. UTC | #3 
On Wed, Oct 09, 2024 at 10:44:38AM -0300, Vinicius Peixoto wrote:
> Hi Greg,
> 
> On 10/9/24 06:56, Greg Kroah-Hartman wrote:
> > On Sat, Sep 21, 2024 at 03:06:09PM -0300, Fabricio Gasperin wrote:
> > > Fixes the following compilation error:
> > > 
> > > ERROR: modpost: "fb_io_read" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> > > ERROR: modpost: "fb_io_write" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> > > ERROR: modpost: "fb_io_mmap" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> > > 
> > > Signed-off-by: Fabricio Gasperin <fgasperin@lkcamp.dev>
> > > ---
> > >   drivers/staging/sm750fb/Kconfig | 1 +
> > >   1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/staging/sm750fb/Kconfig b/drivers/staging/sm750fb/Kconfig
> > > index 08bcccdd0f1c..eca1aa43d725 100644
> > > --- a/drivers/staging/sm750fb/Kconfig
> > > +++ b/drivers/staging/sm750fb/Kconfig
> > > @@ -3,6 +3,7 @@ config FB_SM750
> > >   	tristate "Silicon Motion SM750 framebuffer support"
> > >   	depends on FB && PCI && HAS_IOPORT
> > >   	select FB_MODE_HELPERS
> > > +	select FB_IOMEM_FOPS
> > >   	select FB_CFB_FILLRECT
> > >   	select FB_CFB_COPYAREA
> > >   	select FB_CFB_IMAGEBLIT
> > > -- 
> > > 2.46.1
> > > 
> > > 
> > 
> > What is causing this error? What commit created the problem, and why
> > has no one reported it yet?
> 
> This happens because drivers/staging/sm750fb/sm750.c, defines an fb_ops
> structure:
> 
> static const struct fb_ops lynxfb_ops = {
> 	.owner = THIS_MODULE,
> 	FB_DEFAULT_IOMEM_OPS,
> 	...
> };
> 
> FB_DEFAULT_IOMEM_OPS expands to the fb_io_* helpers declared in
> include/linux/fb.h and defined in drivers/video/fbdev/core/fb_io_fops.c;
> however, the latter is gated by FB_IOMEM_FOPS, so when compiling a kernel
> with CONFIG_STAGING=y + CONFIG_FB=m + CONFIG_FB_SM750=m, you get the
> following error:
> 
> ERROR: modpost: "fb_io_read" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> ERROR: modpost: "fb_io_write" [drivers/staging/sm750fb/sm750fb.ko]
> undefined!
> ERROR: modpost: "fb_io_mmap" [drivers/staging/sm750fb/sm750fb.ko] undefined!
> make[2]: *** [scripts/Makefile.modpost:145: Module.symvers] Error 1
> 
> So in order to solve it we select FB_IOMEM_FOPS, much like the other FB_*
> drivers do in drivers/video/fbdev/Kconfig.
> 
> Not entirely sure why this wasn't caught before, but the commit that broke
> the build for sm750fb is 6b180f66c0dd ("fbdev: Provide I/O-memory helpers as
> module"), which made the fb_io_* helpers be built as a separate module
> instead of being bundled in fb.o (which is what sm750fb was relying on). I
> think Fabricio can add a "Fixes:" tag in v2.

Ok, thanks for the explaination.  All of this should go into the
changelog text, and yes, a Fixes: tag is also required.

thanks,

greg k-h
diff mbox series

Patch

diff --git a/drivers/staging/sm750fb/Kconfig b/drivers/staging/sm750fb/Kconfig
index 08bcccdd0f1c..eca1aa43d725 100644
--- a/drivers/staging/sm750fb/Kconfig
+++ b/drivers/staging/sm750fb/Kconfig
@@ -3,6 +3,7 @@  config FB_SM750
 	tristate "Silicon Motion SM750 framebuffer support"
 	depends on FB && PCI && HAS_IOPORT
 	select FB_MODE_HELPERS
+	select FB_IOMEM_FOPS
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT