topic Re: i.MX8Plus v4l2 Feature Control Api in i.MX Processors

i.MX8Plus v4l2 Feature Control Api

marcus-castlepeakinc — Tue, 22 Feb 2022 23:36:31 GMT

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?

Re: i.MX8Plus v4l2 Feature Control Api

Zhiming_Liu — Wed, 23 Feb 2022 02:31:32 GMT

Can you send me the code you change?

Re: i.MX8Plus v4l2 Feature Control Api

marcus-castlepeakinc — Wed, 23 Feb 2022 02:39:40 GMT

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?

Re: i.MX8Plus v4l2 Feature Control Api

Zhiming_Liu — Wed, 23 Feb 2022 02:57:41 GMT

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

Re: i.MX8Plus v4l2 Feature Control Api

marcus-castlepeakinc — Wed, 23 Feb 2022 03:10:29 GMT

Ok. So in the above definition of

viv_private_ioctl

What should the value of jsonResponse be after calling viv_private_ioctl?