amdgpu_vcn_decode_buffer
struct amdgpu_vcn_decode_buffer *decode_buffer = NULL;
ib_pack_in_dw = sizeof(struct amdgpu_vcn_decode_buffer) / sizeof(uint32_t)
ib->ptr[ib->length_dw++] = sizeof(struct amdgpu_vcn_decode_buffer) + 8;
decode_buffer = (struct amdgpu_vcn_decode_buffer *)&(ib->ptr[ib->length_dw]);
ib->length_dw += sizeof(struct amdgpu_vcn_decode_buffer) / 4;
memset(decode_buffer, 0, sizeof(struct amdgpu_vcn_decode_buffer));