STRUCT VDEC_H264_VSI(9)

💖 struct vdec_h264_vsi(9) 💖

okay bestie, welcome to the Kernel API Manual ✨ — yes we're reading kernel docs together, this is our bonding era 🫶

🌸 NAME 🌸

struct vdec_h264_vsi — it's the shared memory for decode information exchange between VPU and Host, no cap 💅

So here's the tea: the memory is allocated by the VPU, then mapped to the Host inside vpu_dec_init(), and freed in vpu_dec_deinit() by the VPU. literally the whole lifecycle, managed for you 🎀

And because kernel people love abbreviations, here's the legend iykyk:

• AP-W/R — AP is the writer/reader on this item
• VPU-W/R — VPU is the write/reader on this item

ngl keep those letters in your head, every member below tells you who's allowed to touch it 👀

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✨ SYNOPSIS ✨

struct vdec_h264_vsi {
    u64 pred_buf_dma;
    u64 mv_buf_dma[H264_MAX_MV_NUM];
    struct vdec_h264_dec_info dec;
    struct vdec_pic_info pic;
    struct v4l2_rect crop;
    struct mtk_h264_dec_slice_param h264_slice_params;
 };

look at her. six members. main character energy 👑 copy it exactly, don't be cute with it 🙈

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🦋 Members 🦋

• pred_buf_dma — HW working prediction buffer dma address. that's (AP-W, VPU-R) — the AP writes it, the VPU reads it, that's the whole arrangement 💫
• mv_buf_dma — HW working motion vector buffer dma address, and yes it's an array [H264_MAX_MV_NUM] because one buffer was never gonna be enough 😭 (AP-W, VPU-R)
• dec — the decode information 💜 (AP-R, VPU-W) — so the VPU writes, AP reads. flip-flop from the two above, keep up bestie 🩷
• pic — picture information 🌈 (AP-R, VPU-W)
• crop — crop information 🎀 (AP-R, VPU-W)
• h264_slice_params — the parameters that hardware use to decode 🔥 like, the actual instructions, the moment of truth, the reason we're all here ⭐

vibe check: three members are AP-writes/VPU-reads, three are VPU-writes/AP-reads. do not mix them up or it's giving 💀

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🌟 SEE ALSO 🌟

• Kernel file ./drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_h264_req_if.c — go read the source, it ate 💅
• struct vdec_h264_dec_info(9)
• struct vdec_h264_slice_inst(9)

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and that's the page, bestie 🧚💖 this little gem lives over at ./drivers/media/platform/media... and the manual's dated October 2026 — so yeah, it's from the future, iconic behavior honestly 🦋✨ periodt 💅