ioctl failed

OlivierG · ‎02-25-2025

Hi

On an IMX93evk card with Yocto
I tested the code below intended to do an image acquisition on the /dev/video device connected to a RPI-CAM-MIPI camera
https://docs.nxp.com/bundle/UM11933/page/topics/rpi-cam-mipi_overview.html

The calls to the ioctl function fail.
Curiously OpenCv makes the same calls and they do not fail
What did I miss?

int main() {
const char *device = "/dev/video0";
int fd = open(device, O_RDWR);
if (fd == -1) {
perror("Opening video device");
return 1;
}

struct v4l2_format format;
format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
format.fmt.pix.width = 640;
format.fmt.pix.height = 480;
format.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
format.fmt.pix.field = V4L2_FIELD_INTERLACED;

if (ioctl(fd, VIDIOC_S_FMT, &format) < 0) {
perror("Setting Pixel Format");
return 1;
}

struct v4l2_requestbuffers req;
memset(&req, 0, sizeof(req));
req.count = 1;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;

if (ioctl(fd, VIDIOC_REQBUFS, &req) < 0) {
perror("Requesting Buffer");
return 1;
}

struct v4l2_buffer buf;
memset(&buf, 0, sizeof(buf));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = 0;

if (ioctl(fd, VIDIOC_QUERYBUF, &buf) < 0) {
perror("Querying Buffer");
return 1;
}

OlivierG · ‎03-04-2025

hi

I solved this problem using

https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/173737/1/v4lcap.c

Greetings

Olivier

在原帖中查看解决方案

JosephAtNXP · ‎02-25-2025

Hi,

Thank you for your interest in NXP Semiconductor products,

Are you able to replicate the camera preview in your setup?

$ media-ctl -p

$ v4l2-ctl --list-devices

List the supported pixel formats:

$ v4l2-ctl -d0 --list-formats
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture Multiplanar
...

List the supported image resolutions:

$ v4l2-ctl -d0 --list-framesizes YUYV
ioctl: VIDIOC_ENUM_FRAMESIZES
Size: Discrete 1920x1080
...

Capture the camera data and save them to a file using the "v4l2-ctl" command. The supported pixel formats and resolutions are listed above. Here is an example to capture the 1280x800 YUYV camera data:

$ v4l2-ctl -d0 --set-fmt-video=width=1280,height=800,pixelformat=YUYV --stream-mmap=4 --stream-count=10 --stream-to=test.yuv

Capture the camera data, preview them on screen or save them to a file using the "gstreamer" commands:

# preview on screen
$ gst-launch-1.0 -v v4l2src device=/dev/video0 ! "video/x-raw,format=YUY2,width=1280,height=800" ! queue ! waylandsink

Regards

OlivierG · ‎03-03-2025

Hi

I have done the followings commands

# media-ctl -p

Media controller API version 6.6.23

Media device information

------------------------

driver mxc-md

model FSL Capture Media Device

serial

bus info platform:42800000.bus:camera

hw revision 0x0

driver version 6.6.23

Device topology

- entity 1: mxc_isi.0 (16 pads, 2 links, 0 routes)

type V4L2 subdev subtype Unknown flags 0

pad0: Sink

<- "mxc-mipi-csi2.0":4 [ENABLED]

pad1: Sink

pad2: Sink

pad3: Sink

pad4: Sink

pad5: Sink

pad6: Sink

pad7: Sink

pad8: Sink

pad9: Sink

pad10: Sink

pad11: Sink

pad12: Source

-> "mxc_isi.0.capture":0 [ENABLED]

pad13: Source

pad14: Source

pad15: Sink

- entity 18: mxc_isi.0.capture (1 pad, 1 link)

type Node subtype V4L flags 0

device node name /dev/video0

pad0: Sink

<- "mxc_isi.0":12 [ENABLED]

- entity 22: mxc-mipi-csi2.0 (8 pads, 2 links)

type Node subtype V4L flags 0

device node name /dev/v4l-subdev0

pad0: Sink

<- "ap1302_mipi 2-003c":0 [ENABLED,IMMUTABLE]

pad1: Sink

pad2: Sink

pad3: Sink

pad4: Source

-> "mxc_isi.0":0 [ENABLED]

pad5: Source

pad6: Source

pad7: Source

- entity 31: ap1302_mipi 2-003c (1 pad, 1 link, 0 routes)

type V4L2 subdev subtype Unknown flags 0

pad0: Source

-> "mxc-mipi-csi2.0":0 [ENABLED,IMMUTABLE]

# v4l2-ctl --list-devices

FSL Capture Media Device (platform:42800000.bus:camera):

/dev/media0

mxc-isi-cap_v1 (platform:4ae40000.isi:cap_devic):

/dev/video0

# v4l2-ctl -d0 --list-formats

ioctl: VIDIOC_ENUM_FMT

Type: Video Capture Multiplanar

[0]: 'RGBP' (16-bit RGB 5-6-5)

[1]: 'RGB3' (24-bit RGB 8-8-8)

[2]: 'BGR3' (24-bit BGR 8-8-8)

[3]: 'YUYV' (YUYV 4:2:2)

[4]: 'YUV4' (32-bit A/XYUV 8-8-8-8)

[5]: 'NV12' (Y/UV 4:2:0)

[6]: 'NM12' (Y/UV 4:2:0 (N-C))

[7]: 'YM24' (Planar YUV 4:4:4 (N-C))

[8]: 'XR24' (32-bit BGRX 8-8-8-8)

[9]: 'AR24' (32-bit BGRA 8-8-8-8)

# v4l2-ctl -d0 --list-framesizes YUYV

ioctl: VIDIOC_ENUM_FRAMESIZES

Size: Discrete 1920x1080

Size: Discrete 1280x800

Size: Discrete 1280x720

Size: Discrete 640x480

# v4l2-ctl -d0 --set-fmt-video=width=1280,height=800,pixelformat=YUYV --stream-mmap=4 --stream-count=10 --stream-to=test.yuv

# ls -l test.yuv

-rw-r--r-- 1 root root 20480000 Feb 25 02:55 test.yuv

#gst-launch-1.0 -v v4l2src device=/dev/video0 ! "video/x-raw,format=YUY2,width=1280,height=800" ! queue ! waylandsink

i have a display on xwindows

When i launch code with the OpenCV video capture function with log debug level

cv::VideoCapture camera(0, cv::CAP_V4L2);

I get

[DEBUG:0@0.030] global cap_v4l.cpp:1005 open VIDEOIO(V4L2:/dev/video0): opening...

[DEBUG:0@0.030] global cap_v4l.cpp:1021 open VIDEOIO(V4L2:/dev/video0): deviceHandle=14

[DEBUG:0@0.031] global cap_v4l.cpp:1089 tryIoctl VIDEOIO(V4L2:/dev/video0): tryIoctl(14, VIDIOC_QUERYCAP(2154321408), failIfBusy=1)

[DEBUG:0@0.031] global cap_v4l.cpp:1097 tryIoctl VIDEOIO(V4L2:/dev/video0): call ioctl(14, VIDIOC_QUERYCAP(2154321408), ...) => 0 errno=0 (Success)

[DEBUG:0@0.031] global cap_v4l.cpp:1089 tryIoctl VIDEOIO(V4L2:/dev/video0): tryIoctl(14, VIDIOC_G_FMT(3234878980), failIfBusy=1)

[DEBUG:0@0.031] global cap_v4l.cpp:1097 tryIoctl VIDEOIO(V4L2:/dev/video0): call ioctl(14, VIDIOC_G_FMT(3234878980), ...) => 0 errno=0 (Success)

[DEBUG:0@0.031] global cap_v4l.cpp:1089 tryIoctl VIDEOIO(V4L2:/dev/video0): tryIoctl(14, VIDIOC_S_FMT(3234878981), failIfBusy=1)

[DEBUG:0@0.031] global cap_v4l.cpp:1097 tryIoctl VIDEOIO(V4L2:/dev/video0): call ioctl(14, VIDIOC_S_FMT(3234878981), ...) => 0 errno=0 (Success)

[DEBUG:0@0.031] global cap_v4l.cpp:1089 tryIoctl VIDEOIO(V4L2:/dev/video0): tryIoctl(14, VIDIOC_S_PARM(3234616854), failIfBusy=1)

[DEBUG:0@0.031] global cap_v4l.cpp:1097 tryIoctl VIDEOIO(V4L2:/dev/video0): call ioctl(14, VIDIOC_S_PARM(3234616854), ...) => 0 errno=0 (Success)

[DEBUG:0@0.031] global cap_v4l.cpp:1089 tryIoctl VIDEOIO(V4L2:/dev/video0): tryIoctl(14, VIDIOC_G_PARM(3234616853), failIfBusy=1)

[DEBUG:0@0.031] global cap_v4l.cpp:1097 tryIoctl VIDEOIO(V4L2:/dev/video0): call ioctl(14, VIDIOC_G_PARM(3234616853), ...) => 0 errno=0 (Success)

ioctl with VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_S_PARM, VIDIOC_G_PARM work

OlivierG · ‎03-04-2025

hi

I solved this problem using

https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/173737/1/v4lcap.c

Greetings

Olivier