After the upgrade to bookworm/sid, the battery level is not anymore shown. Trying to read most files in /sys/class/power_supply/qcom-battmgr-bat/ returns error "No such device"
Downgrading to the previous kernel (the one in the install image) with its own dtb file does not solve this issue, so it must be "something else", but I'm not sure what. The "specific" packages that were removed are: qrtr, replaced by qrtr-tools from Debian pd-mapper, replaced by protection-domain-mapper from Debian firmware-lenovo, replaced by firmware-qcom-soc from Debian The latter package ships a /lib/firmware/qcom/sc8280xp/LENOVO21BX/battmgr.jsn which looks like it would be the necessary firmware for the battery management to work, but I don't know how to check if it is actually loaded successfully. A "modinfo qcom_battmgr" doesn't show that it has declared that it would use that firmware file... I see on https://lore.kernel.org/linux-firmware/378be5b0-59e2-cfcf-84b5-b49ab01e8...@lenovo.com/T/ that there is supposed to be a symlink from /usr/lib/firmware/qcom/LENOVO/21BX to ../sc8280cp/LENVO/21BX but adding that symlink manually doesn't help. I notice that the qcom-specific rmtfs service fails to start... It looks for /sys/bus/platform/drivers/qcom-q6v6-mss doesn't find it. "modprobe qcom_q6v5_mss" creates that directory, but then rmtfs wants a "remoteproc" directory, doesn't find it.
