config.txt core_freq=499 causes camera error

[CarlFK]

Describe the bug

setting core_freq=499 causes the camera to error.

Steps to reproduce the behaviour

attach pi camera
apt install rpicam-apps-lite
libcamera-hello
(works. good)

vim /boot/firmware/config.txt
add
core_freq=499
reboot

libcamera-hello
...
[0:00:32.157091886] [791] ERROR V4L2 v4l2_videodevice.cpp:1906 /dev/video0[13:cap]: Failed to start streaming: Invalid argument

dmesg
[ 251.039813] unicam fe801000.csi: failed to set up VPU clock

Device (s)

Raspberry Pi 4 Mod. B

System

https://downloads.raspberrypi.org/raspios_lite_armhf/images/raspios_lite_armhf-2024-03-15/2024-03-15-raspios-bookworm-armhf-lite.img.xz

07:48:28 pi@pi3:~ $ cat /etc/rpi-issue
Raspberry Pi reference 2024-03-15
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, 11096428148f0f2be3985ef3126ee71f99c7f1c2, stage2

07:51:48 pi@pi3:~ $ vcgencmd version
Feb 29 2024 12:24:53
Copyright (c) 2012 Broadcom
version f4e2138c2adc8f3a92a3a65939e458f11d7298ba (clean) (release) (start)

07:52:15 pi@pi3:~ $ uname -a
Linux pi3 6.6.20+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.6.20-1+rpt1 (2024-03-07) aarch64 GNU/Linux

Logs

No response

Additional context

I have over 10 pies w/camears, all running the same everything. core_freq=250 works fine on all but one. seems odd. there is a chance the camera is different as not all cameras were bought at the same time.

dmesg
[ 251.039813] unicam fe801000.csi: failed to set up VPU clock

which seems to come from:

linux/drivers/media/platform/bcm2835/bcm2835-unicam.c

Line 99 in 477f26f

* Unicam must request a minimum of 250Mhz from the VPU clock.

This also seems relevant:
https://github.com/raspberrypi/linux/blob/rpi-6.6.y/drivers/media/platform/bcm2835/bcm2835-unicam.c#L98-L102