[SOLVED] Blank screen (backlight still on) early in boot process for kernels 4.15*
wildstar84
Status: Interested
Joined: 31 May 2017
Posts: 35
Location: Texas
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I discovered the other day when booting my laptop (HP Elitebook 8400p w/Intel integrated graphics) that latest 4.15 kernels
did NOT recognize my laptop's panel (undocked) (I normally boot up docked w/external monitor), that 2 lines of text appeared, then screen goes BLANK and does NOT come back on until suspending/resuming, then switching to a console and back to X (everything else still running properly, no errors). The panel is 1600x900, the monitor 1920x1080. I use the kernel "modesetting" driver for i915. Both 4.15 kernels I had fail, but all prev. kernels work fine.

Anyway, after much T&E, I solved by turning OFF "fastboot" in /etc/initramfs-tools/modules (i915) and in
/etc/defaut/grub (and reran update-initramfs -u -k 4.15.0-9.1-liquorix-amd64,
then update-grub). Pbm. does not manifest when booting docked with the lid
closed, but failed when booting undocked OR docked with the lid open. It appears to be a regression in the "fastboot"
option of the i915 driver for kernels 4.15+.

/etc/initramfs-tools/modules:
intel_agp
#i915 fastboot=1
i915 fastboot=0

/etc/defaut/grub:
GRUB_CMDLINE_LINUX_DEFAULT="...i915.fastboot=0"

Hope this helps someone else
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techAdmin
Status: Site Admin
Joined: 26 Sep 2003
Posts: 3912
Location: East Coast, West Coast? I know it's one of them.
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Thanks for the tips, might help someone.
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