How to fix blinking/deactivating display output with KMS/Linux 4.17 on Sharp HDMI 1080p TV?
 

Hi, I'm running a server with a 35" Sharp HDMI TV and an ASUS K53E laptop. The TV seems to want to keep itself at either 1080p or 800x600@75 Hz. The problem with this is, after I mount my root partition via cryptsetup the TV screen blinks like crazy for a few seconds (switching from initramfs video mode to 1080p) and goes black unless I use "nomodeset i915.modeset=0" on the GRUB command line.

I looked at help pages describing my problem and tried inserting the i915 and intel_agp modules into the initramfs for early KMS. That just made it worse and I couldn't even see to unlock the root partition after that. I've tried fiddling with my TV's display settings, I've tried xrandr, reinstalling/downgrading the kernel, forcing the usage of HDMI-1 via the GRUB command line, and even using LiveUSB to really make this a distro-/kernel- independent problem.

My old HDMI TV worked just fine this way with a connection to the laptop. I have no idea what this problem might be other than, and I'm most likely wrong, KMS interacting badly with the TV's picture settings. Am I screwed for using this until I get the internal laptop display cable repaired?

If you are using Plymouth, try removing it altogether, or simply disabling it via plymouth.enable=0 on kernel cmdline.

If the TV is new enough for free return, consider returning it.

Either nomodeset or i915.modeset=0 alone guarantees unhappiness with Intel HD Graphics, unless you are content to use your laptop without X. Using both is a redundant disabling of the KMS both competent X drivers require.

What may be needed is explicitly configuring the TV's specific native mode in detail on the kernel cmdline. Maybe the HDMI-1 you tried wasn't the one needed. Without KMS disabled, did you try ? ? ? Any other?

I tried : D, :e does nothing and 1080x1080@60 only results in more blinking with colors all wonky and mismatched.

Oops. that was supposed to be 1920x1080@60. If that doesn't work, try 1920x1080@60i or 1920x1080R@60. One other thing is that some TVs have HDMI ports that are labeled HDMI/DVI. If yours has one you aren't connected to, switch to it.

The new TV might be more sensitive to the cable, so try another.

If nothing works and no other attempts to help show up here, try the xorg-devel mailing list: https://lists.x.org/mailman/listinfo/xorg-devel or xorg help https://lists.x.org/mailman/listinfo/xorg

I did it!! I still don't know what the problem really was, but I came back to it today after a while to think on it.

Found a setting in my TV setup menu that switches audio from analog to digital/HDMI and back again, played around with it to make sure the laptop and TV weren't getting confused trying to use the video port for sound. Didn't seem to have any effect. Then I booted into the screen-flickery version of my system, and typing blind I did "ls /sys/class/drm/*" as root. Having a smartphone handy helped me record what was going by before it disappeared and there was no HDMI-1.

But there *is* a /sys/class/drm/card0-HDMI-A-1. :D

So I went back to the GRUB command line after a reboot, pressed e to make it "video=HDMI-A-1:e video=LVDS-1:d" and it actually displays now. No bad colors, no automatic TV blinkies/disappearance after cryptsetup and I can get into the graphical desktop.

All I need to do now is mess with the display resolution because the TTYs are both cutting off words that move past the edge of the screen and doing what looks like refusing to scroll up automatically after hitting bottom.

I feel like such an idiot because it was so easy and all I missed on the command line was an A! It's been haunting me for months and I guess that was the solution?!? Lol