The more recent GPU "firmware" releases contain useful power saving features for the Raspberry Pi 4, as can be seen from the release history at https://github.com/raspberrypi/firmware ... aster/boot under the tag firmware.vcgencmd version
Aug 15 2019 12:03:51
Copyright (c) 2012 Broadcom
version 9f8431fb7839c7f00f52b81f5822ddab2b31d0db (clean) (release) (start)
It would be nice if the package linux-firmware-raspi2 could be updated to the latest stable VideoCore "firmware" release.