How to get two USB webcams to operate simultaneously on Raspberry Pi 4 running openSUSE Leap 15.2?

How do I get two USB webcams to operate simultaneously on a Raspberry Pi 4 running openSUSE Leap 15.2? I ultimately want this to work with [Motion](https://motion-project.github.io) and seem to have eliminated that as I also fail with just ffplay from the command line. I have two [webcams](https://www.amazon.co.uk/gp/product/B015VE4KP0) plugged in to a [powered USB hub](https://www.amazon.co.uk/gp/product/B07KFDFT4D) . Both webcams work independently but not together. As a test, plugging the webcams directly in to the Pi or removing power from the hub gives me **device descriptor read/64 error -110** so the hub *is* providing power correctly. If I start the first cam as follows, I get a picture: # ffplay -f v4l2 /dev/video0 But when I then start the second, I don't get a picture (the first will continue to work); we just wait here and don't appear to timeout (can't say I've waited for more than a few minutes, though): # ffplay -loglevel debug -f v4l2 /dev/video2 ffplay version 3.4.8 Copyright (c) 2003-2020 the FFmpeg developers built with gcc 7 (SUSE Linux) configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --incdir=/usr/include/ffmpeg --extra-cflags='-fmessage-length=0 -grecord-gcc-switches -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -g' --optflags='-fmessage-length=0 -grecord-gcc-switches -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -g' --disable-htmlpages --enable-pic --disable-stripping --enable-shared --disable-static --enable-gpl --disable-openssl --enable-avresample --enable-libcdio --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libcelt --enable-libcdio --enable-libdc1394 --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libzimg --enable-libzvbi --enable-vaapi --enable-vdpau --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-version3 --enable-libx264 --enable-libx265 --enable-libxvid libavutil 55. 78.100 / 55. 78.100 libavcodec 57.107.100 / 57.107.100 libavformat 57. 83.100 / 57. 83.100 libavdevice 57. 10.100 / 57. 10.100 libavfilter 6.107.100 / 6.107.100 libavresample 3. 7. 0 / 3. 7. 0 libswscale 4. 8.100 / 4. 8.100 libswresample 2. 9.100 / 2. 9.100 libpostproc 54. 7.100 / 54. 7.100 Initialized opengl renderer. [video4linux2,v4l2 @ 0xffff40000b50] fd:11 capabilities:84a000010 [video4linux2,v4l2 @ 0xffff40000b50] Current input_channel: 0, input_name: Camera 1, input_std: 0 [video4linux2,v4l2 @ 0xffff40000b50] Querying the device for the current frame size [video4linux2,v4l2 @ 0xffff40000b50] Setting frame size to 1280x720 [video4linux2,v4l2 @ 0xffff40000b50] The V4L2 driver changed the pixel format from 0x32315559 to 0x47504A4D [video4linux2,v4l2 @ 0xffff40000b50] Trying to set codec:rawvideo pix_fmt:yuv420p [video4linux2,v4l2 @ 0xffff40000b50] The V4L2 driver changed the pixel format from 0x32315559 to 0x47504A4D [video4linux2,v4l2 @ 0xffff40000b50] Trying to set codec:rawvideo pix_fmt:yuv420p [video4linux2,v4l2 @ 0xffff40000b50] The V4L2 driver changed the pixel format from 0x32315659 to 0x47504A4D [video4linux2,v4l2 @ 0xffff40000b50] Trying to set codec:rawvideo pix_fmt:yuv422p [video4linux2,v4l2 @ 0xffff40000b50] The V4L2 driver changed the pixel format from 0x50323234 to 0x47504A4D [video4linux2,v4l2 @ 0xffff40000b50] Trying to set codec:rawvideo pix_fmt:yuyv422 nan : 0.000 fd= 0 aq= 0KB vq= 0KB sq= 0B f=0/0 Nothing in dmesg; journalctl shows this when first cam is started: Dec 29 16:23:17 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Scheduling inhibition from ":1.14" "My SDL application" with cookie 18 and reason "Playing a game" Dec 29 16:23:22 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Enforcing inhibition from ":1.14" "My SDL application" with cookie 18 and reason "Playing a game" Dec 29 16:23:22 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Added change screen settings Dec 29 16:23:22 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Added interrupt session Dec 29 16:23:22 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Disabling DPMS due to inhibition Dec 29 16:23:22 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Can't contact ck ...And then when the second is started Dec 29 16:24:07 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Scheduling inhibition from ":1.14" "My SDL application" with cookie 19 and reason "Playing a game" Dec 29 16:24:12 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Enforcing inhibition from ":1.14" "My SDL application" with cookie 19 and reason "Playing a game" Dec 29 16:24:12 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Added change screen settings Dec 29 16:24:12 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Added interrupt session Dec 29 16:24:12 shed-pi4.xxx.xxx org_kde_powerdevil: powerdevil: Can't contact ck Which might be the key or a red herring. The jury are still out according to Google! If I stop ffplay for the first cam (video0), then the second 'hung' session (video2) will immediately spring in to life. Other info: # ls -lah /dev/v4l/by-path/ total 0 drwxr-xr-x 2 root root 120 Oct 21 15:01 . drwxr-xr-x 4 root root 80 Oct 21 15:01 .. lrwxrwxrwx 1 root root 12 Oct 21 15:01 platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.4.3:1.0-video-index0 -> ../../video0 lrwxrwxrwx 1 root root 12 Oct 21 15:01 platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.4.3:1.0-video-index1 -> ../../video1 lrwxrwxrwx 1 root root 12 Oct 21 15:01 platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.4.4:1.0-video-index0 -> ../../video2 lrwxrwxrwx 1 root root 12 Oct 21 15:01 platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.4.4:1.0-video-index1 -> ../../video3 # ls -lah /dev/v4l/by-id/ total 0 drwxr-xr-x 2 root root 80 Oct 21 15:01 . drwxr-xr-x 4 root root 80 Oct 21 15:01 .. lrwxrwxrwx 1 root root 12 Oct 21 15:01 usb-HD_Camera_Manufacturer_USB_2.0_Camera-video-index0 -> ../../video0 lrwxrwxrwx 1 root root 12 Oct 21 15:01 usb-HD_Camera_Manufacturer_USB_2.0_Camera-video-index1 -> ../../video1 # hwinfo --usb [Edit] 03: USB 00.1: 0000 Unclassified device [Created at usb.122] Unique ID: VfPh.nrd9O+1TtQ3 Parent ID: 33sj.xvTGa+XkbXF SysFS ID: /devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.4/1-1.4.4/1-1.4.4:1.1 SysFS BusID: 1-1.4.4:1.1 Hardware Class: unknown Model: "ARC International USB 2.0 Camera" Hotplug: USB Vendor: usb 0x05a3 "ARC International" Device: usb 0x9310 "USB 2.0 Camera" Driver: "uvcvideo" Driver Modules: "uvcvideo" Speed: 480 Mbps Module Alias: "usb:v05A3p9310d0000dcEFdsc02dp01ic0Eisc02ip00in01" Config Status: cfg=new, avail=yes, need=no, active=unknown Attached to: #4 (Hub) 05: USB 00.2: 0000 Unclassified device [Created at usb.122] Unique ID: Wi1b.nrd9O+1TtQ3 Parent ID: 33sj.xvTGa+XkbXF SysFS ID: /devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.4/1-1.4.3/1-1.4.3:1.2 SysFS BusID: 1-1.4.3:1.2 Hardware Class: unknown Model: "ARC International USB 2.0 Camera" Hotplug: USB Vendor: usb 0x05a3 "ARC International" Device: usb 0x9310 "USB 2.0 Camera" Driver: "snd-usb-audio" Driver Modules: "snd_usb_audio" Speed: 480 Mbps Module Alias: "usb:v05A3p9310d0000dcEFdsc02dp01ic01isc01ip00in02" Driver Info #0: Driver Status: snd_usb_audio is active Driver Activation Cmd: "modprobe snd_usb_audio" Config Status: cfg=new, avail=yes, need=no, active=unknown Attached to: #4 (Hub) # lsusb -t /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 5000M |__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=uas, 5000M /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 480M |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M |__ Port 1: Dev 8, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M |__ Port 1: Dev 8, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M |__ Port 3: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 12M |__ Port 3: Dev 5, If 1, Class=Human Interface Device, Driver=usbhid, 12M |__ Port 4: Dev 4, If 0, Class=Hub, Driver=hub/4p, 480M |__ Port 4: Dev 7, If 1, Class=Video, Driver=uvcvideo, 480M |__ Port 4: Dev 7, If 2, Class=Audio, Driver=snd-usb-audio, 480M |__ Port 4: Dev 7, If 0, Class=Video, Driver=uvcvideo, 480M |__ Port 4: Dev 7, If 3, Class=Audio, Driver=snd-usb-audio, 480M |__ Port 3: Dev 6, If 2, Class=Audio, Driver=snd-usb-audio, 480M |__ Port 3: Dev 6, If 0, Class=Video, Driver=uvcvideo, 480M |__ Port 3: Dev 6, If 3, Class=Audio, Driver=snd-usb-audio, 480M |__ Port 3: Dev 6, If 1, Class=Video, Driver=uvcvideo, 480M # v4l2-ctl --list-devices --verbose USB 2.0 Camera: HD USB Camera (usb-0000:01:00.0-1.4.3): /dev/video0 /dev/video1 USB 2.0 Camera: HD USB Camera (usb-0000:01:00.0-1.4.4): /dev/video2 /dev/video3 VIDIOC_QUERYCAP: ok I've been Googling all afternoon but so far drawn a blank. How can I get both cameras up and running simultaneously? I'm hoping that if I can get it working with ffplay then it will work with Motion. Thanks in advance.