On Sun, Mar 12, 2017 at 05:59:28PM -0300, Mauro Carvalho Chehab wrote:

Yet, udev/systemd has some rules that provide an unique name for V4L
devices at /lib/udev/rules.d/60-persistent-v4l.rules. Basically, it
runs a small application (v4l_id) with creates a persistent symling
using rules like this:

	KERNEL=="video*", ENV{ID_SERIAL}=="?*", SYMLINK+="v4l/by-id/$env{ID_BUS}-$env{ID_SERIAL}-video-index$attr{index}"

Those names are stored at /dev/v4l/by-path.

This doesn't help:

$ ls -Al /dev/v4l/by-id/
total 0
lrwxrwxrwx 1 root root 13 Mar 12 19:54 usb-Sonix_Technology_Co.__Ltd._USB_2.0_Camera-video-index0 -> ../../video10
$ ls -Al /dev/v4l/by-path/
total 0
lrwxrwxrwx 1 root root 12 Mar 12 19:54 platform-2040000.vpu-video-index0 -> ../../video0
lrwxrwxrwx 1 root root 12 Mar 12 19:54 platform-2040000.vpu-video-index1 -> ../../video1
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index0 -> ../../video2
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index1 -> ../../video3
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index2 -> ../../video4
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index3 -> ../../video5
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index4 -> ../../video6
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index5 -> ../../video7
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index6 -> ../../video8
lrwxrwxrwx 1 root root 12 Mar 12 20:53 platform-capture-subsystem-video-index7 -> ../../video9
lrwxrwxrwx 1 root root 13 Mar 12 19:54 platform-ci_hdrc.0-usb-0:1:1.0-video-index0 -> ../../video10

The problem is the "platform-capture-subsystem-video-index" entries.
These themselves change order.  For instance, I now have:

- entity 72: ipu1_csi0 capture (1 pad, 1 link)
             type Node subtype V4L flags 0
             device node name /dev/video6

which means it's platform-capture-subsystem-video-index4.  Before, it
was platform-capture-subsystem-video-index2.

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