STRUCT DRM_SHADOW_PLANE_STATE(9)

🦋 struct drm_shadow_plane_state(9) — the glow-up 💅

okay so bestie, welcome to the struct drm_..._plane_state(9) page (that's the manual name, we're keeping it iconic), and honestly? this one's a little gem. it's from the Kernel API Manual, and it's all about giving shadow-buffer planes their moment. ✨

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🌸 NAME 🌸

struct drm_shadow_plane_state — literally the plane state for planes that have shadow buffers. that's it, that's the vibe. 🎀

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✨ SYNOPSIS ✨

here's the structure, exactly as it lives, no edits, no cap:

struct drm_shadow_plane_state {
    struct drm_plane_state base;
    struct drm_format_conv_state fmtcnv_state;
    struct iosys_map map[DRM_FORMAT_MAX_PLANES];
    struct iosys_map data[DRM_FORMAT_MAX_PLANES];
 };

look at her. so organized. main character energy fr fr. 👑

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🫶 Members 🫶

• base — the plane state itself. the blueprint, the foundation, the base if you will. 💖
• fmtcnv_state — the format-conversion state. and lowkey there's a lot going on here:
  • it's per-plane state for format conversion.
  • it holds flags for copying shadow buffers into backend storage.
  • it also holds temporary storage for format conversion. like a lil scratchpad, but make it DRM. 🎀
• map — mappings of the plane's framebuffer BOs in to kernel address space.

heads up bestie: the memory mappings stored in map should be established in the plane's prepare_fb callback, and removed in the cleanup_fb callback. set them up, tear them down — no leaving them lying around, that's not the vibe. 🙈

• data — the address of each framebuffer BO's data.

this is the address of the data stored in each mapping. and here's the catch: this is different for framebuffers with non-zero offset fields. so like, don't assume it's just the mapping address, okay? ⭐

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💜 Description 💜

so, for planes that use a shadow buffer, struct drm_shadow_plane_state provides the regular plane state plus mappings of the shadow buffer into kernel address space. the regular state ate, and the mappings came along for the ride. periodt. 🔥

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🌈 SEE ALSO 🌈

• Kernel file ./include/drm/drm_gem_atomic_helper.h
• DRM_SHADOW_PLANE_MAX_WIDTH(9)
• DRM_SHADOW_PLANE_MAX_HEIGHT(9)
• to_drm_shadow_plane_state(9)
• DRM_GEM_SHADOW_PLANE_FUNCS(9)
• DRM_GEM_SHADOW_PLANE_HELPER_FUNCS(9)
• DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS(9)

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okay that's the whole page! 💖 this lil baddie lives over in ./include/drm, dated October 2026, and it's filed under struct drm_..._plane_state(9). go forth and shadow-buffer responsibly, bestie — you've got this. 🦋🌸🫶