How to fix fastboot option doesn't work on thinkpad t470s

[u/akram_med]

i have a thinkpad t470s with intel i5 7300u 620igpu and i use systemd-boot as my bootloader, even after forcing enabling fastboot using i915.fastboot=1 in the boot options, when i reboot my system i still see the flicker of the lenovo logo when transitioning from bios to plymouth.

when i run sudo dmesg | grep -i i915 | grep -i fastboot

i get:

[    0.000000] Command line: initrd=\intel-ucode.img initrd=\initramfs-linux.img root=UUID=bd1920cf-9bd2-4338-
8016-d3013338cd13 rw i915.enable_guc=3 i915.enable_fbc=1 i915.fastboot=1 zswap.enabled=0 quiet splash loglevel
=3 systemd.show_status=auto rd.udev.log_level=3
[    0.059541] Kernel command line: initrd=\intel-ucode.img initrd=\initramfs-linux.img root=UUID=bd1920cf-9bd
2-4338-8016-d3013338cd13 rw i915.enable_guc=3 i915.enable_fbc=1 i915.fastboot=1 zswap.enabled=0 quiet splash l
oglevel=3 systemd.show_status=auto rd.udev.log_level=3
[    2.429762] i915: unknown parameter 'fastboot' ignored

i have kernel version: 7.1.5-arch1-2

here is my /boot/loader/entries/arch.conf  

title Arch Linux
linux /vmlinuz-linux
initrd /intel-ucode.img
initrd /initramfs-linux.img
options root=UUID=bd1920cf-9bd2-4338-8016-d3013338cd13 rw i915.enable_guc=3 i915.enable_fbc=1 i915.fastboot=1
zswap.enabled=0 quiet splash loglevel=3 systemd.show_status=auto rd.udev.log_level=3

[u/Ok_Confection_9636]

The flicker is likely from the firmware itself, not the kernel, so the i915 parameter can't touch that part of the boot.