Timestamps for v4l2 camera sensor

[shreyas.pa]

Hi,

I have a Jetson Xavier NX, L4T version we are using is 32.5.
We are using radar ‘iwr6843isk’ to capture raw data and pass it to Jetson. I would like to get time stamps from the driver we use for each frames.
I went through some of the related topisc

How does v4l2_buffer->timestamp to system OS timestamp

If your problem is don’t know how to get the timestamp. You can reference to the v4l2-ctl tools source code is public. Current the timestamp is Monotonic mode if you want to change it you have to modify the vi4_fops.c nvidia@nvidia-desktop:~$ v4l2-ctl --stream-mmap --stream-count=3 -d /dev/video0 --verbose VIDIOC_QUERYCAP: ok VIDIOC_REQBUFS: ok VIDIOC_QUERYBUF: ok VIDIOC_QBUF: ok VIDIOC_QUERYBUF: ok VIDIOC_QBUF: ok VIDIOC_QUERYBUF: ok VIDIOC_QBUF: ok VIDIOC_QUERYBUF: ok VIDIOC_QBUF: ok VIDIOC…

V4l2 Timestamp always 0 after VIDIOC_DQBUF (l4t r32.2.1)

vb2_buffer is defined in videobuf2-core.h which is only available in the kernel source. Trying to include it in user space causes a whole host of issues. When that failed I spent some time trying to cherry pick out the struct definitions (vb2_buffer, vb2_queue, vb2_plane, etc) but that quickly got down to some includes only available in the kernel source. I don’t think that using vb2_buffer (or vb2_v4l2_buffer) is an option in user space.

v4l2 timestamp issure

hello xuhui1.wang, please refer to below to demonstrate how to check the timestamp. offset_ns is used to calculate the capture timestamp from system time. you might also check below example for offset_ns to compensate the capture timestamp. root@tegra-ubuntu:~# cat /sys/devices/system/clocksource/clocksource0/offset_ns 9045955168 to add debug prints to gather kernel time. diff --git a/drivers/media/platform/tegra/camera/vi/vi5_fops.c b/drivers/media/platform/tegra/camera/vi/vi5_fops.c inde…

Also I have tried printing the time stamp for start and end of frame from the vi driver. But I want to get the exact timestamping from the driver. How can this be achieved?

[ShaneCCC]

Try to trace the …/kernel/nvidia/drivers/media/platform/tegra/camera/vi/vi5_fops.c

[JerryChang]

hello shreyas.pa,

to be more specific,
you should check VI-5 kernel driver, $public_sources/kernel_src/kernel/nvidia/drivers/media/platform/tegra/camera/vi/vi5_fops.c

please check below for start-of-frame timestamp, which sending to user-space.

static void vi5_capture_dequeue(struct tegra_channel *chan,
        struct tegra_channel_buffer *buf)
{

..
        vb->vb2_buf.timestamp = descr->status.sof_timestamp;