Processor Expert Softwareのトピックuvcvideo module takes time to detect logitech webcam

uvcvideo module takes time to detect logitech webcam

shubham_sharmaa — Sun, 07 May 2023 20:45:35 GMT

The following custom init script is executed by the kernel on i.mx8mm processor using yocto zeus.

The issue is after loading the necessary kernel modules and mounting the required file system. Camera detection by the uvcvideo is after 2-3 seconds then camera opens. I want to open camera immediately when this script runs. Any idea what's going on in this scenario?

Attached are the logs cameraopening.txt

#!/bin/sh # Load the necessary kernel modules for the camera modprobe videobuf2-v4l2 modprobe videodev modprobe uvcvideo # Mount the Linux kernel virtual filesystems mount none -t proc /proc # Ensure devtmpfs is mounted, it must be done manually with initramfs # Setup PTY infrastructure mkdir /dev/pts mount none -t devpts /dev/pts # Set any necessary environment variables export DISPLAY=:0.0 mkdir -p /run/user/$(id -u) XDG_RUNTIME_DIR=/run/user/$(id -u) export XDG_RUNTIME_DIR while true; do echo "--------------------camera is starting------------------------------------" ./sbin/uvc_stream -o test.avi v4l2-ctl --list-devices # Get the exit status of the pipeline status=$? # If the pipeline exited with an error, log a message and wait a few seconds before restarting it if [[ $status != 0 ]]; then sleep 0.00001 fi done

Re: uvcvideo module takes time to detect logitech webcam

Chavira — Mon, 08 May 2023 01:49:20 GMT

Hi @shubham_sharmaa !

Thank you for contacting NXP Support!

Probably you have your device tree wrong.

Please check our Application Note Explaining the device tree and how works.

AN5125, Introduction to Device Trees - Application Note (nxp.com)

Best Regards

Chavira.

Re: uvcvideo module takes time to detect logitech webcam

shubham_sharmaa — Mon, 08 May 2023 03:43:33 GMT

Hi @Chavira Thanks for replying so quick. I will look into device trees. But may I ask to get your context why you think there is problem with the device tree? Why i am asking is because this device tree is provided by the board vendor.

Re: uvcvideo module takes time to detect logitech webcam

Chavira — Tue, 09 May 2023 14:55:51 GMT

HI @shubham_sharmaa

Device trees are tree data structures, which describe the hardware configuration allowing a common kernel to be booted with different pin
settings for different boards or configurations. Device tree files use the .dtb extension. The configuration for a
device tree can be found in the Linux source code under arch/arm/boot/dts in the *.dts files

Normally the device tree is provided by the board vendor.

If you have a board different of our evks please contact the support of your board vendor.