[PATCH] drm/fbdev-helper: Fix deletion of stub for drm_fb_helper_gem_is_fb()

[PATCH] drm/fbdev-helper: Fix deletion of stub for drm_fb_helper_gem_is_fb()

[mike.marciniszyn]

From: Mike Marciniszyn <mmarcini@meta.com>

When CONFIG_DRM_FBDEV_EMULATION  is not defined this error results
when building amdgpu_display.c with CONFIG_DRM_AMDGPU:

error: call to undeclared function 'drm_fb_helper_gem_is_fb'; ISO C99 and
later do not support implicit function
declarations [-Wimplicit-function-declaration]

 1777 |  if (!drm_fb_helper_gem_is_fb(dev->fb_helper, fb->obj[0])) {

Cc: stable@vger.kernel.org
Signed-off-by: Mike Marciniszyn <mmarcini@meta.com>
---
 include/drm/drm_fb_helper.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index bf391903443d..7f9ad421af3f 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -273,6 +273,13 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
 int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper);
 bool drm_fb_helper_gem_is_fb(const struct drm_fb_helper *fb_helper,
 			     const struct drm_gem_object *obj);
+#else
+static inline bool drm_fb_helper_gem_is_fb(const struct drm_fb_helper *fb_helper,
+					   const struct drm_gem_object *obj)
+{
+	return false;
+}
+
 #endif

 #endif
--
2.43.0

Re: [PATCH] drm/fbdev-helper: Fix deletion of stub for drm_fb_helper_gem_is_fb()

[Dmitry Ilvokhin]

On Fri, May 01, 2026 at 04:43:13PM -0400, mike.marciniszyn@gmail.com wrote:
> From: Mike Marciniszyn <mmarcini@meta.com>
> 
> When CONFIG_DRM_FBDEV_EMULATION  is not defined this error results
> when building amdgpu_display.c with CONFIG_DRM_AMDGPU:
> 
> error: call to undeclared function 'drm_fb_helper_gem_is_fb'; ISO C99 and
> later do not support implicit function
> declarations [-Wimplicit-function-declaration]
> 
>  1777 |  if (!drm_fb_helper_gem_is_fb(dev->fb_helper, fb->obj[0])) {
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Mike Marciniszyn <mmarcini@meta.com>

Just hit the same problem, thanks for the fix.

Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>

Re: [PATCH] drm/fbdev-helper: Fix deletion of stub for drm_fb_helper_gem_is_fb()

[Mike Marciniszyn]

On Thu, May 07, 2026 at 06:10:12PM +0000, Dmitry Ilvokhin wrote:
> On Fri, May 01, 2026 at 04:43:13PM -0400, mike.marciniszyn@gmail.com wrote:
> > From: Mike Marciniszyn <mmarcini@meta.com>
> >
> > When CONFIG_DRM_FBDEV_EMULATION  is not defined this error results
> > when building amdgpu_display.c with CONFIG_DRM_AMDGPU:
> >
> > error: call to undeclared function 'drm_fb_helper_gem_is_fb'; ISO C99 and
> > later do not support implicit function
> > declarations [-Wimplicit-function-declaration]
> >
> >  1777 |  if (!drm_fb_helper_gem_is_fb(dev->fb_helper, fb->obj[0])) {
> >
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Mike Marciniszyn <mmarcini@meta.com>
>
> Just hit the same problem, thanks for the fix.
>
> Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>

Thanks, but actually there was already a fix.

Take a look at linux.git/master:

commit 927011b65a875302d08709bbe82eaf4d0d96c5d5
Author: Yury Norov <ynorov@nvidia.com>
Date:   Mon Apr 27 22:49:41 2026 -0400

    drm/amdgpu: fix build for CONFIG_DRM_FBDEV_EMULATION=n

I encountered this in net-next, but the above has yet to be put into net-next.

Mike

Re: [PATCH] drm/fbdev-helper: Fix deletion of stub for drm_fb_helper_gem_is_fb()

[Dmitry Ilvokhin]

On Thu, May 07, 2026 at 03:12:02PM -0400, Mike Marciniszyn wrote:
> On Thu, May 07, 2026 at 06:10:12PM +0000, Dmitry Ilvokhin wrote:
> > On Fri, May 01, 2026 at 04:43:13PM -0400, mike.marciniszyn@gmail.com wrote:
> > > From: Mike Marciniszyn <mmarcini@meta.com>
> > >
> > > When CONFIG_DRM_FBDEV_EMULATION  is not defined this error results
> > > when building amdgpu_display.c with CONFIG_DRM_AMDGPU:
> > >
> > > error: call to undeclared function 'drm_fb_helper_gem_is_fb'; ISO C99 and
> > > later do not support implicit function
> > > declarations [-Wimplicit-function-declaration]
> > >
> > >  1777 |  if (!drm_fb_helper_gem_is_fb(dev->fb_helper, fb->obj[0])) {
> > >
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Mike Marciniszyn <mmarcini@meta.com>
> >
> > Just hit the same problem, thanks for the fix.
> >
> > Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
> 
> Thanks, but actually there was already a fix.
> 
> Take a look at linux.git/master:
> 
> commit 927011b65a875302d08709bbe82eaf4d0d96c5d5
> Author: Yury Norov <ynorov@nvidia.com>
> Date:   Mon Apr 27 22:49:41 2026 -0400
> 
>     drm/amdgpu: fix build for CONFIG_DRM_FBDEV_EMULATION=n
> 
> I encountered this in net-next, but the above has yet to be put into net-next.
> 
> Mike

Indeed. Thanks, Mike.