HDMI resets from time to time on Intel Graphics

DexterLB · 2018-08-04 12:41:03

Hello,
I have an Asus RoG laptop with Intel Graphics connected to the HDMI port.

I use an 8m HDMI cable to connect it to a screen. About a month ago, the screen started to reset (turns off for a couple of seconds and then back on) once about every minute. My first idea was a faulty cable, so I swapped it for a brand new one. The flickers remained absolutely the same. I've tried the same cable + screen with a different laptop, and it works fine.

Here's what I know so far:

- xrandr says the mode is 1920x1200 59.95Hz. Monitor says it supports 1920x1200, 60Hz
- the problem persists with both the intel and modesetting drivers, and also in bare framebuffer console with KMS
- `i915.enable_psr=0` doesn't do anything
- moving the cable around, twisting it etc doesn't cause a flickering or change the apparent probability of a reset

My hypothesis is that the frequency is not exact for some reason and the display wants to resync from time to time. Unfortunately, it doesn't support frequencies other than 60Hz, so I can't test with a lower frequency.

What can I do to further track down the problem?

seth · 2018-08-04 14:14:50

You could add a modeline for 60Hz, but I assume 59.95Hz is EDID gathered and the monitor is just talking consumer BS.
Is the replacement cable also 8m? Did you try a short one?
What's the corresponding dmesg output?
Does this only happen on battery or also on PSU?
Tried "i915.enable_dc=0"?

ewaller · 2018-08-04 14:53:38

Point of history. In the US, the frame rate for black and white television (RS-170) was 60Hz. When color (RS-170a) was introduced in the 1960's, the frame rate was actually changed to 59.95Hz. The change was done to break up moiré artifacts of adding color. It might be real.

seth · 2018-08-04 15:48:03

And this is why it's called "Never The Same Color" … :-P

DexterLB · 2018-08-04 16:59:10

Ah. I seem to have forgotten a crucial piece of information: The screen is connected via an HDMI->DVI dongle. The second laptop seems to use an iternal DP-output which is converted to HDMI, therefore supports 60.0Hz. The first (problematic) laptop has a genuine HDMI output and apparently defaults to some consumer standard with 59.95Hz refresh frequency.

Also, "i915.enable_dc=0" doesn't help, and neither does switching between battery/AC power.

A shorter cable works fine, so this must be a compound issue between power levels / frequency / cable length.

seth · 2018-08-04 20:35:42

https://wiki.archlinux.org/index.php/Xr … esolutions

The adapter may muddy the EDID data, but I worry that the HDMI signal isn't strong enough for converter + cable.

DexterLB · 2018-08-04 20:37:55

I'm afraid you're right - the other laptop seems to also work fine on 59.95Hz and there's no difference when I force 60Hz.

Now the question is why it used to work and suddenly stopped.

seth · 2018-08-04 21:29:13

Did you try to downgrade the kernel, or the LTS one?

Arch Linux

#1 2018-08-04 12:41:03

HDMI resets from time to time on Intel Graphics

#2 2018-08-04 14:14:50

Re: HDMI resets from time to time on Intel Graphics

#3 2018-08-04 14:53:38

Re: HDMI resets from time to time on Intel Graphics

#4 2018-08-04 15:48:03

Re: HDMI resets from time to time on Intel Graphics

#5 2018-08-04 16:59:10

Re: HDMI resets from time to time on Intel Graphics

#6 2018-08-04 20:35:42

Re: HDMI resets from time to time on Intel Graphics

#7 2018-08-04 20:37:55

Re: HDMI resets from time to time on Intel Graphics

#8 2018-08-04 21:29:13

Re: HDMI resets from time to time on Intel Graphics

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