Only after a recent dist-upgrade
I ran into an issue w/ the screen staying dark b/c of pwm-backlight backlight: unable to request PWM
on my Reform using the RCM4 Processor Module Adapter and a Raspberry Pi CM4:
# dmesg | grep backlight
[ 6.202666] OF: /backlight: #pwm-cells = 3 found 2
[ 6.202710] of_pwm_get(): can't parse "pwms" property
[ 6.202721] pwm-backlight backlight: unable to request PWM
I found a related Raspberry Pi forum post: Kernel 6.6.0 - PWM seems not working/available
As it stands, it seems upstream change has broken it:
I was able to fix —patch— it like so:
git clone https://source.mnt.re/reform/mnt-reform-raspberry-pi-cm4-som
cd mnt-reform-raspberry-pi-cm4-som
vi rcm4-overlay.dts
- pwms = <&pwm 0 10000>;
+ pwms = <&pwm 0 10000 0>;
./mkoverlay.sh
sudo cp /boot/firmware/overlays/rcm4-overlay.dtbo /boot/firmware/overlays/rcm4-overlay.dtbo.old
sudo cp rcm4-overlay.dtbo /boot/firmware/overlays/rcm4-overlay.dtbo
sudo reboot
I’m reporting this here, b/c at least for now, it seems I couldn’t figure out how to contribute this patch to reform/mnt-reform-raspberry-pi-cm4-som.
hth