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

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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

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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.

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