RPi3: why there is no video device?

[danergo]

Kernel:

# uname -a
Linux rpi3 6.12.1-v8+ #1822 SMP PREEMPT Mon Nov 25 14:19:09 GMT 2024 aarch64 GNU/Linux

OS:

# cat /etc/issue
Debian GNU/Linux 12 \n \l

There is no video device:

# ls /dev/video*
ls: cannot access '/dev/video*': No such file or directory

Tried:

# modprobe bcm2835_v4l2
# dmesg
...
[  497.039120] mc: Linux media interface: v0.10
[  497.131499] videodev: Linux video capture interface: v2.00
[  497.158118] vc_sm_cma: module is from the staging directory, the quality is unknown, you have been warned.
[  497.159926] bcm2835_vc_sm_cma_probe: Videocore shared memory driver
[  497.159948] [vc_sm_connected_init]: start
[  497.160737] [vc_sm_connected_init]: installed successfully
[  497.170244] bcm2835_mmal_vchiq: module is from the staging directory, the quality is unknown, you have been warned.
[  497.183513] bcm2835_v4l2: module is from the staging directory, the quality is unknown, you have been warned.

config.txt (GPU related):

# cat /boot/config.txt  | grep gpu
gpu_mem_256=32
gpu_mem_512=32
gpu_mem_1024=32

What do you suggest?

Update

Tried to increase gpu_mems to 128,256,256: same result.

Updated kernel to

Linux rpi3 6.12.22-v8+ #1872 SMP PREEMPT Tue Apr 15 15:46:58 BST 2025 aarch64 GNU/Linux

But still. Drives me crazy. Why on earth I don't have video device?

Final goal
I wish to use v4l2m2m hw acceleration with ffmpeg:

ffmpeg -c:v h264_v4l2m2m -rtsp_transport tcp -i 'rtsp://camera_access' -c:v h264_v4l2m2m -pix_fmt yuv420p -b:v 128k -an test.mp4

Now ffmpeg error:

[h264_v4l2m2m @ 0x2a041da0] Could not find a valid device
[h264_v4l2m2m @ 0x2a041da0] can't configure decode

[danergo]

Note: I tried this:

dtoverlay=vc4-kms-v3d

But ffmpeg still claims:

[h264_v4l2m2m @ 0x32cca020] Could not find a valid device
[h264_v4l2m2m @ 0x32cca020] can't configure decoder