Understanding where does XrandR command get its values from

Matthi · 03-25-2019, 04:56 PM

Hi

Feels like a firmware issue which I'm not sure If I need to classify this question as Hardware or Software

Using HP t530 Thin clients in the office
Using Dell U2417H monitors (display port to display port or mini display port)

Running the XrandR command from the HP OS 7.0.0 (Linux) it pulls out all the possible resolution that the monitors support

My issue is there is a bunch of resolution respecting the 16:9 aspect ratio that are missing beside 1920x1080

Dell support says it doesn't come from the Dell monitor and they don't support Linux so their monitor drivers which they don't know if it may solve the issue wouldn't work anyway

HP support says these resolutions are coming from the Dell firmware because of the obvious fact that if I plug a Viewsonic as my second monitor, I get 27 possible resolutions while the Dell only provided 14

The Dell monitor works fine under Windows 7 but Windows may as well don't care about what the monitor may provide if providing anything

Well the question is simple
using the xrandr command under Linux, where does it poll for the list of possible resolution for a monitor

If its the OS providing that list, how would I change that list for specific monitors?
If its the monitor, then I need to irritate Dell until they transfer me to their firmware department...

Thank you

Matthi · 03-25-2019, 06:41 PM

If I read

https://wiki.archlinux.org/index.php...ed_resolutions

I understand there is a way to permanently add a resolution...

I'm not sure it is precise as to where it did pull out the list of resolution available for a specific monitor though
"Adding undetected resolutions
Due to buggy hardware or drivers, your monitor's correct resolutions may not always be detected by xrandr. For example, the EDID data block queried from the monitor may be incorrect
"

So the monitor does provide the list of resolution if I understand this correctly?

michaelk · 03-25-2019, 06:48 PM

Yes, they do. Typical support people have no clue...

https://en.wikipedia.org/wiki/Extend...ification_Data

mrmazda · 03-26-2019, 12:03 AM

Quote:

Originally Posted by Matthi

using the xrandr command under Linux, where does it pool for the list of possible resolution for a monitor

Did you mean poll rather than pool? NAICT, modes shown by xrandr are generated from the display's EDID.

Quote:

If its the OS providing that list, how would I change that list for specific monitors?

Connect it to a different GPU is one way. Maybe xrandr's newmode/addmode would do it, something I've never found necessary.

Quote:

If its the monitor, then I need to irritate Dell until they transfer me to their firmware department...

Don't blame Dell for this. Bad as its customer support can be if it knows you are a Linux user, this looks like either a combination GPU/software issue, or entirely a GPU issue. This is from a Dell 2913wm display connected to a (recent) Intel HD 630 GPU (with non-wide & low resolution modes omitted):

Code:

> xrandr
Screen 0: minimum 320 x 200, current 2560 x 2520, maximum 8192 x 8192
DP-2 connected 2560x1080+0+0 (normal left inverted right x axis y axis) 673mm x 284mm
   2560x1080     60.26*+
   1920x1080     60.00  
   1680x1050     59.95  
   1400x900      59.98  
   1280x800      59.81

This is from the same 2913wm display connected to an (old) ATI HD 6450 GPU (with non-wide & low resolution modes omitted):

Code:

> xrandr
Screen 0: minimum 320 x 200, current 2560 x 1080, maximum 16384 x 16384
DP-1 connected primary 2560x1080+0+0 (normal left inverted right x axis y axis) 673mm x 284mm
   2560x1080     60.00*+
   1920x1080     59.96    60.00    60.00    50.00    59.94    59.93    24.00    23.98  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.95    59.88  
   1600x900      59.94    59.95    59.82  
   1440x900      59.98  
   1400x900      59.96    59.88  
   1440x810      59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1280x720      60.00    59.99    59.86    60.00    50.00    59.94    59.74  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82

The above was extracted from a data collection using 5 different displays and 4 different GPUs:
http://fm.no-ip.com/Tmp/Linux/Xorg/Matthi/
It seems clear as far as these tests went that AMD/ATI GPU automagic produces more available modes than Intel on any particular display. If you need a particular non-native display mode, you might need a different GPU.

Possibly choice of DDX or server version might have an effect. I tested tonight only using the default modesetting DDX, and only used openSUSE 15.0 with server 1.19.6 on the four different PCs.

HTH

Matthi · 03-26-2019, 08:58 AM

Great input people

Yes I meant poll

So if I understand correctly

The GPU requests the monitor for the available resolutions/refresh rate etc using the HDMI or Display Port cable
The GPU is telling the OS what are the possible choices

Understanding that the Viewsonic attached to the same computer/GPU is providing the whole list of possible resolutions we know it is not a "full scale" issue with the GPU

Then it comes down to:
Is the Dell monitor giving all the possible resolutions
or is the GPU not understanding the list giving to it from a Dell's monitor or that specific Dell monitor

So on my end, I'll get the details on that GPU.
I'll try to get Dell's firmware department to confirm what is the list provided by that monitor.

mrmazda · 03-26-2019, 09:29 AM

https://static.bhphotovideo.com/lit_files/148619.pdf shows a very limited selection of widescreen modes for the U2417H.

Code:

inxi -Gxx

run from within Xorg (e.g. Xterm) would provide relevant GPU, kernel driver, DDX & high level driver info for sharing here (by wrapping in code tags, [#] directly above the input window).

Matthi · 03-26-2019, 11:54 AM

This is the list provided for my 2 Dell monitors
(Inxi isn't installed on that HP Linux OS apparently.....will see what I can do about that)

Code:

[xrandr]
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
DisplayPort-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
   1920x1080     60.00*+  60.00    50.00    59.94    24.00    23.98  
   1600x1200     60.00  
   1680x1050     60.00  
   1280x1024     75.02    60.02  
   1440x900      60.00  
   1280x800      60.00  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  

DisplayPort-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
   1920x1080     60.00*+  60.00    50.00    59.94    24.00    23.98  
   1600x1200     60.00  
   1680x1050     60.00  
   1280x1024     75.02    60.02  
   1440x900      60.00  
   1280x800      60.00  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DisplayPort-2 disconnected (normal left inverted right x axis y axis)

It feels it is following page 11 in the document provided although there is some discrepancies

Display Mode Horizontal 
Frequency 
(kHz)

Vertical 
Frequency 
(Hz)

Pixel Clock 
(MHz)

Sync Polarity 
(Horizontal/
Vertical) 
720 x 400 31.5 70.0 28.3 -/+
VESA, 640 x 480 31.5 60.0 25.2 -/- 
VESA, 640 x 480 37.5 75.0 31.5 -/-
VESA, 800 x 600 37.9 60.3 40.0 +/+
VESA, 800 x 600 46.9 75.0 49.5 +/+
VESA, 1024 x 768 48.4 60.0 65.0 -/-
VESA, 1024 x 768 60.0 75.0 78.8 +/+
VESA, 1152 x 864 67.5 75.0 108.0 +/+
VESA, 1280 x 1024 64.0 60.0 108.0 +/+
VESA, 1280 x 1024 80.0 75.0 135.0 +/+
VESA, 1600 x 1200 75.0 60.0 162.0 +/+
VESA, 1920 x 1080 67.5 60.0 148.5 +/+

If I plug the Viewsonic as a second monitor

Code:

[xrandr]
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
DisplayPort-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
   1920x1080     60.00*+  60.00    50.00    59.94    24.00    23.98  
   1600x1200     60.00  
   1680x1050     60.00  
   1280x1024     75.02    60.02  
   1440x900      60.00  
   1280x800      60.00  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  

DisplayPort-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm
   1920x1080     60.00*+  74.97    50.00    59.94  
   1600x1200     65.00    60.00  
   1680x1050     59.95  
   1680x945      59.96  
   1400x1050     74.87    59.98  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1440x900      74.98    59.89  
   1280x960      60.00  
   1366x768      59.79  
   1360x768      60.02  
   1280x800      74.93    59.81  
   1152x864      75.00  
   1280x768      74.89    59.87  
   1280x720      60.00    50.00    59.94  
   1440x576      50.00  
   1024x768      75.03    70.07    60.00  
   1440x480      60.00    59.94  
   1024x576      59.98  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   720x576       50.00  
   848x480       60.00  
   720x480       60.00    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94  
   720x400       70.08  
   720x240       60.12    60.05  
DisplayPort-2 disconnected (normal left inverted right x axis y axis)

Processor is a AMD Embedded_Series G-Series GX-215JJ Radeon-R2E

Also to keep in mind, the funny thing is that if I change my resolution to 1366, the Viewsonic is going to accept that resolution, not the Dell even though it is applied to both monitors.... but if without rebooting, I unplug the Viewsonic and plug the Dell, the Dell that uses the Viewsonic Displayport is going to use 1366 resolution.....until I reboot...like if the OS already accepted this to be a good resolution to send to the output and no longer check if its a resolution supported on the monitor

mrmazda · 03-26-2019, 02:43 PM

Please use [code] tags [ # ] for pasting commands and their output.

What instigated this thread? Are these thin client users trying to utilize lower resolution modes merely to make desktop objects and text larger? This may be simple for users to figure out how to do, but it's definitely not utilizing the quality available from native mode. 1366x768 and 1280x720 are just so crude, ugly, same as 1024x768 and lower.

Matthi · 03-26-2019, 03:01 PM

I've just edited and added the []

Well some user are older and their eyes are not as ....good as before....
So yes people, most of the time of a certain age would like bigger stuff in their monitor and as a company we'll just get one type of monitor...
The chosen Dell we're the best price/design/hd monitor respecting what we were looking for, so gradually everyone will be using 2 of those ....well unless we can't fix this issue...and have to move away from Dell...

1600x900 would be the first step which respect the 16:9 aspect ratio of that monitor...

After that you have the 1366x768 which is almost 16:9 ...we're talking less than a pixel difference...

both of them are not available at the moment

mrmazda · 03-26-2019, 03:28 PM

Quote:

Originally Posted by Matthi

I've just edited and added the []

Incorrectly. Test a reply to post #6 to see how a correct result is implemented. The [ # ] right above the input window is how you can apply the tags more simply, by selecting the text to be wrapped, then clicking the button.

Matthi · 03-27-2019, 04:49 PM

Oh ok, lol I didn't know what you we're talking about until I saw that button in the reply window...
I've added the [CO-DE][/CO-DE] without the -

Dell hardware department is having me transferred to Dell software team...

So far to me it is

Figure out if Dell monitor firmware is providing that to the GPU
If it does, then contact AMD Radeon because it means the GPU is not understanding Dell's data
If it doesn't, it mean the Dell monitor needs to be fixed...

Backup solution is adding manually those missing resolution

mrmazda · 03-27-2019, 05:25 PM

Try creating /etc/X11/xorg.conf.d/50-monitor.conf (/etc/X11/xorg.conf.d/ is an optional directory) with this content:

Code:

Section "Monitor"
	Identifier	"DefaultMonitor"
	VendorName	"Dell"
	ModelName	"U2417H"
	HorizSync	30-83
	VertRefresh	50-75
	Option	"PreferredMode"	"1366x768"
EndSection

Maybe the EDID for these are broken or missing. If it doesn't help, try 1360 instead of 1366.

Matthi · 03-28-2019, 01:06 PM

I didn't found etc at the root although I was able to create that file under

writable\etc\X11\xorg.conf.d\50-monitor.conf

Code:

Section "Monitor"
	Identifier	"DefaultMonitor"
	VendorName	"Dell"
	ModelName	"U2417H"
	HorizSync	30-83
	VertRefresh	50-75
	Option	"PreferredMode"	"1366x768"
EndSection

Section "Monitor"
	Identifier	"DefaultMonitor"
	VendorName	"Dell"
	ModelName	"U2417H"
	HorizSync	30-83
	VertRefresh	50-75
	Option	"PreferredMode"	"1600x900"
EndSection

Did reboot but it is still not showing using XRANDR unfortunately

Matthi · 03-28-2019, 01:21 PM

I was able to follow theses steps from:
http://ubuntuhandbook.org/index.php/...buntu-desktop/

It was working because it was added to the drop down list
(new version 7.1.0 OS is actually just showing the resolution discovered by xrandr)

until I've rebooted...because it probably poll again the list from the xrandr...

but I haven't modified the profile entry, so I'm working on that

mrmazda · 03-28-2019, 01:34 PM

You can only have one PreferredMode. Did you check for error messages from duplicating Identifier? What did xrandr show? Where exactly did you put it? "writable\etc\X11\xorg.conf.d\50-monitor.conf" might be legitimate for some purpose on a Windows or DOS boot, but /etc/X11/xorg.conf.d/50-monitor.conf is where it has to go to have a chance to work, and with only one instance of Identifier "DefaultMonitor" among however many Section "Monitor"s you choose to have.

You can also put your CVT-generated mode into a 50-monitor.conf file.

Code:

man xorg.conf