How can I use system_link API in hdvpss for DM8168

hi everyone !

 I have a problem to use SYSTEM_LINK;

1.I have create new system link.but it does not working.

the init code like this:

#define    SYSTEM_LINK_ID_SRC_DETECT       VPSS_LINK(54) 

Int32 SrcDetectLink_init()
{
    Int32 status;
    System_LinkObj linkObj;
    SrcDetectLink_Obj *pObj;
	
    /* register link with system API */

    pObj = &gSrcDetectLink_obj;

    memset(pObj, 0, sizeof(*pObj));

    linkObj.pTsk = &pObj->tsk;
    linkObj.linkGetFullFrames = NULL;//SrcDetectLink_getFullFrames;
    linkObj.linkPutEmptyFrames = NULL;//SrcDetectLink_putEmptyFrames;
    linkObj.getLinkInfo = NULL;//SrcDetectLink_getInfo;

    status = System_registerLink(SYSTEM_LINK_ID_SRC_DETECT, &linkObj);
    UTILS_assert(status == FVID2_SOK);

    /** Create link task, task remains in IDLE state
        CaptureLink_tskMain is called when a message command is received
    */

    status = Utils_tskCreate(&pObj->tsk,
                             SrcDetectLink_tskMain,
                             SRC_DETECT_LINK_TSK_PRI,
                             gSrcDetectLink_tskStack,
                             SRC_DETECT_LINK_TSK_STACK_SIZE, pObj, "SRCDETECT");
    UTILS_assert(status == FVID2_SOK);

	Vps_printf("SrcDetectLink_init DONE!\n");

    return status;
}

when I call System_linkControl(srcDetectId, SRCDETECT_LINK_CMD_DETECT_VIDEO, NULL, 0, TRUE) to send message . but it not working.

2.new system link not working .So I add new cmd to capture link.

code like this:

#define CAPTURE_LINK_CMD_IDENTIFY_INPUT			(0x100A)

		case CAPTURE_LINK_CMD_IDENTIFY_INPUT:
			Vps_printf("Get CAPTURE_LINK_CMD_IDENTIFY_INPUT MESSAGE!\n");
			Vps_printf("Do nothing now!\n");
			Utils_tskAckOrFreeMsg(pRunMsg, status);
			break;

add this in function CaptureLink_tskRun(); then use

	System_linkControl(gVcapModuleContext.captureId, CAPTURE_LINK_CMD_IDENTIFY_INPUT, NULL, 0, TRUE); in A8 side. But I find this also not working.

So I do not what is wrong?

can somebody help me to tell how to create new system link in HDVPSS package..

Thank You very much!