[PATCH] [linux-next mismerge] drm/fbdev-emulation: restore drm_fb_helper_gem_is_fb() dummy

[PATCH] [linux-next mismerge] drm/fbdev-emulation: restore drm_fb_helper_gem_is_fb() dummy

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

linux-next contains an incorrect merge of the drm tree and the amdgpu tree,
which have conflicting patches from Thomas Zimmermann:

drivers/gpu/drm/amd/amdgpu/amdgpu_display.c: In function 'amdgpu_display_suspend_helper':
drivers/gpu/drm/amd/amdgpu/amdgpu_display.c:1777:22: error: implicit declaration of function 'drm_fb_helper_gem_is_fb'; did you mean 'drm_fb_helper_from_client'? [-Wimplicit-function-declaration]
 1777 |                 if (!drm_fb_helper_gem_is_fb(dev->fb_helper, fb->obj[0])) {

drivers/gpu/drm/radeon/radeon_device.c: In function 'radeon_suspend_kms':
drivers/gpu/drm/radeon/radeon_device.c:1592:22: error: implicit declaration of function 'drm_fb_helper_gem_is_fb'; did you mean 'drm_fb_helper_from_client'? [-Wimplicit-function-declaration]
 1592 |                 if (!drm_fb_helper_gem_is_fb(dev->fb_helper, fb->obj[0])) {
      |                      ^~~~~~~~~~~~~~~~~~~~~~~
      |                      drm_fb_helper_from_client

The newly added drm_fb_helper_from_client() stub is in fact needed, while all
the other stubs are correctly removed.

Fixes: 6d438685340d ("drm/fbdev-emulation: Remove empty placeholders")
Fixes: 1837c76b780a ("drm/amdgpu: Move test for fbdev GEM object into generic helper")
Fixes: 9c63d743d5cc ("Merge branch 'drm-next' of https://gitlab.freedesktop.org/agd5f/linux.git")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/drm/drm_fb_helper.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index bf391903443d..80c81fdb04a2 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -273,6 +273,14 @@ 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
-- 
2.39.5

Claude review: [linux-next mismerge] drm/fbdev-emulation: restore drm_fb_helper_gem_is_fb() dummy

[Claude Code Review Bot]

Overall Series Review

Subject: [linux-next mismerge] drm/fbdev-emulation: restore drm_fb_helper_gem_is_fb() dummy
Author: Arnd Bergmann <arnd@kernel.org>
Patches: 1
Reviewed: 2026-03-14T07:12:57.339546

---

This is a single patch fixing a **linux-next merge conflict**, not a patch targeting drm-next directly. The patch addresses a build failure caused by conflicting commits from two different trees (drm and amdgpu) being merged together in linux-next:

1. The drm tree (commit `6d438685340d`) removed empty placeholder/stub functions from `drm_fb_helper.h`, including the `#else` block with stubs for `!CONFIG_DRM_FBDEV_EMULATION`.
2. The amdgpu tree (commit `1837c76b780a`) added a new function `drm_fb_helper_gem_is_fb()` and callers in `amdgpu_display.c` and `radeon_device.c`.
3. The merge (`9c63d743d5cc`) didn't properly resolve the interaction — the new function's declaration exists in the `#ifdef CONFIG_DRM_FBDEV_EMULATION` block, but the corresponding `#else` stub was not added, so builds with `CONFIG_DRM_FBDEV_EMULATION=n` fail.

The fix is correct and straightforward. This is a standard linux-next fixup patch.

---
Generated by Claude Code Patch Reviewer

Claude review: [linux-next mismerge] drm/fbdev-emulation: restore drm_fb_helper_gem_is_fb() dummy

[Claude Code Review Bot]

Patch Review

**Correctness: Good.** The patch adds an `#else` static inline stub that returns `false` for `drm_fb_helper_gem_is_fb()`. This is the correct semantic — when fbdev emulation is disabled, there is no fbdev framebuffer, so "is this GEM object the fbdev FB?" should always return `false`.

```c
+static inline bool
+drm_fb_helper_gem_is_fb(const struct drm_fb_helper *fb_helper,
+			const struct drm_gem_object *obj)
+{
+	return false;
+}
```

The function signature matches the declaration shown in the diff context (lines 98-99):
```c
 bool drm_fb_helper_gem_is_fb(const struct drm_fb_helper *fb_helper,
 			     const struct drm_gem_object *obj);
```

**One observation:** Looking at the current drm-next tree (`drm_fb_helper.h:274`), the `#ifdef CONFIG_DRM_FBDEV_EMULATION` block currently has no `#else` at all — it just ends with `#endif`. The patch's context lines show `drm_fb_helper_gem_is_fb` declared at lines 98-99 before the `#else`, which means this patch is based on the linux-next merged state where the amdgpu tree's additions are already present. This is expected for a linux-next fixup and wouldn't apply to drm-next alone.

**Commit message: Well written.** It clearly explains the conflicting commits, includes the compiler error messages, references all three relevant Fixes: tags, and identifies precisely which stub needs restoration.

**No issues found.** The patch is a correct and minimal fix for the linux-next build breakage.

---
Generated by Claude Code Patch Reviewer