solve error msg 'Possible missing firmware /lib/firmware/i915/'

OS: Debian Stretch

There's error msg as following during upgrade due to lack of Intel Linux Graphics firmware files. Against bin name, download and install files on below page accordingly:

Error msg:
update-initramfs: Generating /boot/initrd.img-4.9.0-1-amd64
W: Possible missing firmware /lib/firmware/i915/bxt_dmc_ver1_07.bin for module i915
W: Possible missing firmware /lib/firmware/i915/skl_dmc_ver1_26.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_dmc_ver1_01.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_ver9_14.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_ver8_7.bin for module i915
W: Possible missing firmware /lib/firmware/i915/skl_guc_ver6_1.bin for module i915

Download page:
https://01.org/linuxgraphics/downloads/firmware

Eg: bxt_dmc_ver1_07.bin matches Broxton/bxt/DMC - Ver 1.07

Instructions:
$ tar xf filename.tar.bz2
$ sudo bash ./install.sh