I have Samsung ultrawide display that I use via HDMI on a Dell Latitude E6540 with Debian Buster (Debian Stable) on it.
It can support a resolution of 3840 x 1080, but currently is only set to Full HD 1920 x 1080, and that is the maximum resolution that it will support.
The picture now does not fill the whole screen, there are black vertical bars left and right on the monitor.

Below the output of xrandr, as you can see it has a very strange thing where it says that current is 3840 x 1080, but the highest available mode is 1920 x 1080.

How can I use the full resolution?

The laptop has two graphics cards:

1. Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06)
2. Radeon HD 8790M

This is a hybrid GPU system (laptop) so both GPUs get routed to the same display normally and have to be manually selected (via xrandr --setprovideroutputsource and using DRI_PRIME=1)

The laptop has only 2 video connectors: HDMI and VGA output.


xrandr output:
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 8192 x 8192
eDP-1 connected primary 1920x1080+1920+0 (normal left inverted right x axis y axis) 344mm x 194mm
1920x1080 60.01 + 59.97* 59.96 59.93 40.00
1680x1050 59.95 59.88
1600x1024 60.17
1400x1050 59.98
1600x900 59.99 59.94 59.95 59.82
1280x1024 60.02
1440x900 59.89
1400x900 59.96 59.88
1280x960 60.00
1440x810 60.00 59.97
1368x768 59.88 59.85
1360x768 59.80 59.96
1280x800 59.99 59.97 59.81 59.91
1152x864 60.00
1280x720 60.00 59.99 59.86 59.74
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
960x540 59.96 59.99 59.63 59.82
800x600 60.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
800x512 60.17
700x525 59.98
800x450 59.95 59.82
640x512 60.02
720x450 59.89
700x450 59.96 59.88
640x480 60.00 59.94
720x405 59.51 58.99
684x384 59.88 59.85
680x384 59.80 59.96
640x400 59.88 59.98
576x432 60.06
640x360 59.86 59.83 59.84 59.32
512x384 60.00
512x288 60.00 59.92
480x270 59.63 59.82
400x300 60.32 56.34
432x243 59.92 59.57
320x240 60.05
360x202 59.51 59.13
320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 797mm x 333mm
1920x1080 60.00* 60.00 50.00 59.94 30.00 29.97
1680x1050 59.88
1600x900 60.00
1280x1024 75.02 60.02
1440x900 59.90
1280x800 59.91
1152x864 75.00
1280x720 60.00 60.00 50.00 59.94
1024x768 75.03 70.07 60.00
832x624 74.55
800x600 72.19 75.00 60.32 56.25
720x576 50.00
720x480 60.00 59.94
640x480 75.00 72.81 66.67 60.00 59.94
720x400 70.08
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
VGA-1-2 disconnected (normal left inverted right x axis y axis)

This may not be a software issue, but rather one that can be solved by adjusting the monitor itself.

The monitors I've used have menu buttons that activate controls allowing vertical, horizontal, brightness, and other adjustments. See the monitor's manual.

Also, when posting terminal output, please use "code" tags, which become available when you click the "Go Advanced" button beneath the compose/edit post window; they make terminal output much easier to read.

Sadly, that is not the solution, I just checked. There are no settings such as this, the monitor says it is 1920 x 1080, the computer says the same, the black bars stay. All I can do is stretch (upscale) the picture, which makes it distorted and pixelated, the extra resolution stays unreachable.

This is not my monitor and I'm glad, because I would be forced to not be able to use it. I have not been a fan of super wide and the little love I had for it just died ;-)

I have to boot with a windows SSD if this is a software (Linux) or hardware issue with this laptop.

Thanks for the response.

I'm sorry I couldn't help and I understand how irritating that can be. I faced the same thing with my monitor, but was able to resolve it with the monitor's own settings.

Perhaps someone with more knowledge than I will join this thread.

I just tried with Windows and it works there, the native resolution that automatically gets set:
3440 x 1440
with 49 Hz, and it is working with the integrated GPU intel HD Graphics 4600, so that is not the problem.

One thing that I see is the kernel complaining:
[drm:intel_enable_ddi [i915]] *ERROR* [CONNECTOR:75:HDMI-A-1] Failed to configure sink scrambling/TMDS bit clock ratio

So it is a Linux software issue.

This is on kernel: 4.19.0-8-amd64 #1 SMP Debian 4.19.98-1 (2020-01-26) x86_64 GNU/Linux

I have an ultra wide Dell monitor that has 3440x1440 as a normal resolution and have successfully used Debian Buster with an onboard Intel HD630 so I know Linux has this capability. I have never had any graphical issues with this monitor running any version of Linux or even FreeBSD in the past 2 or 3 years.

I am not familiar with the Intel 4600 - could this be a driver issue maybe? I don't remember explicitly installing any drivers for my Intel GPU - everything just worked.

You know, that has been my experience, most monitors that I have ever used worked flawlessly, I would not even consider checking a monitor for Linux compatibility.
It must be a driver issue and, likely a DRM issue.

A Quick Search for your problem. Yours is first, but more interesting results. Also for windows users this seems to be an issue sometimes...

Let's discuss more after you go through some of those.
... I have my eyes on the askubuntu article.
What does "DRM" stand for in this case.

Digital Rights Management and doubtful it’s that because you aren’t viewing any copyrighted content, just your desktop. I still think it is an issue of drivers. Could the dual graphics card be an issue?

It could mean Direct Rendering Manager (DRM): a subsystem of the Linux kernel responsible for interfacing with GPUs of modern video cards. DRM exposes an API that user-space programs can use to send commands and data to the GPU and perform operations such as configuring the mode setting of the display.
(partly quoted from wikipedia).

1 members found this post helpful.

Not really, as I said, when I boot windows from an external SSD, it works perfectly and it is running on the intel card.
I have had problems with the digital rights management before, you have to remember that HDMI is encrypted through the cable, to prevent anybody from "stealing video" ;-)
It uses something called HDCP and a display has to be compliant with the standard, otherwise it won't be able to display the video/screen. They call it authentication. It is important to know that HDCP is always active, not just when copyrighted content is displayed, it can't tell so all of it is secured.
https://en.wikipedia.org/wiki/HDMI
I don't know the details about it, but I have had instances where a device did not want to display anything except a solid color screen to a monitor because of non compliance.

But you are right, confusing enough, DRM could also mean this:
https://en.wikipedia.org/wiki/Direct_Rendering_Manager

They seriously did not check for other projects using the same acronym before chosing theirs? Now it will be forever confusing ;-)