Brightness above 64267 results in brightness lower than 0

[non-bin]

Device Information

Framework Laptop 16 (AMD Ryzen™ 7040 Series)
BIOS 04.05

Describe the bug

Since the latest BIOS update, when a brightness above 64267 is requested, it seems to overflow.
I generated this table:

brightness	actual_brightness	Comment
0	3341	I think this is normal
4000	3341
5000	3829
6000	4073
60000	61633
64000	65291	Oh dear...
64267	65535	Uh oh...
64268	0	Ah. The backlight is still on though
65300	0	There is a perceptable brightness change
65500	0	And again
65535	0	This is still darker than asking for 0 brightness

Using this script

b() {
 echo $1 >/sys/class/backlight/amdgpu_bl1/brightness
 cat /sys/class/backlight/amdgpu_bl1/brightness | tr -d '\n'
 printf " | "
 cat /sys/class/backlight/amdgpu_bl1/actual_brightness
}

echo "brightness | actual_brightness"
echo "-|-"
b 0 # 3341
b 4000 # 3341
b 5000 # 3829
b 6000 # 4073
b 60000 # 61633
b 64000 # 65291
b 64267 # 65535
b 64268 # 0
b 65000 # 0
b 65300 # 0
b 65500 # 0
b 65535 # 0

Ideally I would like to keep the new low minimum brightness, just without having to script around the overflow. Could we please just have direct controll over the brightness? Maybe even be able to turn the backlight off?

Example workaround script

if [ "$1" == "" ] || (($1 > 65535)) || (($1 < 0)); then
 echo ERROR: Value is out of range
 exit 1
fi

x=$(($1 - 1268))

if ((x < 0)); then
 echo $((64268 + $1)) >/sys/class/backlight/amdgpu_bl1/brightness
else
 echo $x >/sys/class/backlight/amdgpu_bl1/brightness
fi

Operating System (please complete the following information):

• OS/Distribution: NixOS
• Version: updated yesterday
• Linux Kernel Version: Linux skellybones 7.1.7 #1-NixOS SMP PREEMPT_DYNAMIC Thu Aug 6 17:28:04 UTC 2026 x86_64 GNU/Linux

[debuxxed]

same issue.

[artix@debuxxed ~]$ for v in 62000 63000 64000 64500 65000 65500 65535; do echo $v | sudo tee /sys/class/backlight/amdgpu_bl1/brightness >/dev/null; sleep 1; printf "%s -> " "$v"; cat /sys/class/backlight/amdgpu_bl1/actual_brightness; done
[sudo] password for artix: 
62000 -> 63340
63000 -> 64316
64000 -> 65291
64500 -> 0
65000 -> 0
65500 -> 0
65535 -> 0

[LePat]

Confirmed on FW16 AMD Ryzen AI 9 HX 370/RTX 5070 hybrid mode, BIOS 04.01: same overflow at 64267, found by binary search.