i.MX8Plus v4l2 Feature Control Api

[marcus-castlepeakinc]

Hello.  I'm trying to enable Demosaic feature in v4l2.  I read in i.MX 8M Plus Applications Processor Reference manual, table 13-39 that Demosaic converts RAW Bayer pipeline data to 12-bit RGB.  I am trying to set this with code I leveraged from isp-imx source, vvext.cpp, viv_private_ioctl(int fd, const char *cmd, char *request, char *response), and the only responses I'm seeing from the ioctl calls is "{\"result\": 0}".

Does anyone know if this return json string means demosaic is enabled?  I know my v4l2 buffers contain the same Bayer data as they did before, which leads me to believe the VIDIOC_S_EXT_CTRLS ioctl is not working correctly.  Does anyone know what response *will* be if the ioctl is successful?

[Zhiming_Liu]

Can you send me the code you change?

[marcus-castlepeakinc]

Hello.  I didn't change any code from the original code in vvext.cpp, viv_private_ioctl(int fd, const char *cmd, char *request, char *response):

int viv_private_ioctl(const char *cmd, Json::Value& jsonRequest, Json::Value& jsonResponse) {
    if (!cmd) {
        ALOGE("cmd should not be null!");
        return -1;
    }
    jsonRequest["id"] = cmd;
    jsonRequest["streamid"] = streamid;

    struct v4l2_ext_controls ecs;
    struct v4l2_ext_control ec;
    memset(&ecs, 0, sizeof(ecs));
    memset(&ec, 0, sizeof(ec));
    ec.string = new char[VIV_JSON_BUFFER_SIZE];
    ec.id = V4L2_CID_VIV_EXTCTRL;
    ec.size = 0;
    ecs.controls = &ec;
    ecs.count = 1;

    ::ioctl(fd, VIDIOC_G_EXT_CTRLS, &ecs);

    strcpy(ec.string, jsonRequest.toStyledString().c_str());

    int ret = ::ioctl(fd, VIDIOC_S_EXT_CTRLS, &ecs);
    if (ret != 0)
        return ret;

    ::ioctl(fd, VIDIOC_G_EXT_CTRLS, &ecs);

    Json::Reader reader;
    reader.parse(ec.string, jsonResponse, true);
    delete ec.string;
    ec.string = NULL;
    return jsonResponse["MC_RET"].asInt();
}

Does this code work on the i.MX8Plus?

[Zhiming_Liu]

Hi @marcus-castlepeakinc 

ISP V4L2 user guide shows that V4L2 source code support Demosaic.You can search "Demosaic" in this guide and you will find control code.

https://www.nxp.com.cn/webapp/Download?colCode=IMX8MPISPUV4L2IUG

[marcus-castlepeakinc]

Ok.  So in the above definition of

viv_private_ioctl

What should the value of jsonResponse be after calling viv_private_ioctl?