Same on Ubuntu 18.04 with linux-firmware 1.173.19:
sudo apt-get install linux-firmware --reinstall
update-initramfs: Generating /boot/initrd.img-5.4.0-54-generic
W: Possible missing firmware /lib/firmware/i915/tgl_dmc_ver2_04.bin for module i915
W: Possible missing firmware /lib/firmware/i915/skl_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/glk_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/icl_guc_33.0.0.bin for module i915
update-initramfs: Generating /boot/initrd.img-5.4.0-53-generic
W: Possible missing firmware /lib/firmware/i915/tgl_dmc_ver2_04.bin for module i915
W: Possible missing firmware /lib/firmware/i915/skl_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/glk_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_33.0.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/icl_guc_33.0.0.bin for module i915
Same on Ubuntu 18.04 with linux-firmware 1.173.19:
sudo apt-get install linux-firmware --reinstall
update-initramfs: Generating /boot/initrd. img-5.4. 0-54-generic i915/tgl_ dmc_ver2_ 04.bin for module i915 i915/skl_ guc_33. 0.0.bin for module i915 i915/bxt_ guc_33. 0.0.bin for module i915 i915/kbl_ guc_33. 0.0.bin for module i915 i915/glk_ guc_33. 0.0.bin for module i915 i915/kbl_ guc_33. 0.0.bin for module i915 i915/icl_ guc_33. 0.0.bin for module i915 img-5.4. 0-53-generic i915/tgl_ dmc_ver2_ 04.bin for module i915 i915/skl_ guc_33. 0.0.bin for module i915 i915/bxt_ guc_33. 0.0.bin for module i915 i915/kbl_ guc_33. 0.0.bin for module i915 i915/glk_ guc_33. 0.0.bin for module i915 i915/kbl_ guc_33. 0.0.bin for module i915 i915/icl_ guc_33. 0.0.bin for module i915
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
update-initramfs: Generating /boot/initrd.
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/
W: Possible missing firmware /lib/firmware/