[SOLVED] Trouble outputting 4k at 60hz

JamesNorris · 04-06-2023, 10:14 AM

So the display on my old TV went kaput, so I've had to get a new one. The computer is an HTPC in the living room, running Debian Testing. I have an AMD 5500XT GPU and a Samsung UE50BU8500 TV, which supports resolutions of up to 4096x2160 at 60hz. I'm trying to run at 3840x2160, but apparently it will only run at 30hz. I have bought a new cable, which was probably needed, as the old one is 12 years old and probably wouldn't support HDMI 2.1, but the new cable, which claims to be 8k compatible, and specifically says it is 4k at 60hz compatible. I'm using the HDMI out on the GPU and the eARC HDMI input on the TV...

Code:

james@localhost:~$ inxi -Fxxxmprz
Graphics:
  Device-1: AMD Navi 14 [Radeon RX 5500/5500M / Pro 5500M] vendor: ASUSTeK
    driver: amdgpu v: kernel arch: RDNA-1 pcie: speed: 16 GT/s lanes: 16 ports:
    active: HDMI-A-1 empty: DP-1,DP-2,DP-3 bus-ID: 0a:00.0 chip-ID: 1002:7340
    class-ID: 0300
  Display: x11 server: X.Org v: 1.21.1.7 with: Xwayland v: 22.1.8
    compositor: kwin_x11 driver: X: loaded: amdgpu
    unloaded: fbdev,modesetting,radeon,vesa dri: radeonsi gpu: amdgpu
    display-ID: :0 screens: 1
  Screen-1: 0 s-res: 3840x2160 s-dpi: 96 s-size: 1015x571mm (39.96x22.48")
    s-diag: 1165mm (45.85")
  Monitor-1: HDMI-A-1 mapped: HDMI-A-0 model: Samsung serial: <filter>
    res: 3840x2160 hz: 30 dpi: 52 size: 1872x1053mm (73.7x41.46")
    diag: 1271mm (50.1") modes: max: 3840x2160 min: 720x400
  API: OpenGL v: 4.6 Mesa 22.3.6 renderer: AMD Radeon RX 5500 XT (navi14
    LLVM 15.0.6 DRM 3.49 6.1.0-7-amd64) direct-render: Yes

and xrandr shows this:

Code:

james@localhost:~$ xrandr
Screen 0: minimum 320 x 200, current 3840 x 2160, maximum 16384 x 16384
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
HDMI-A-0 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 1872mm x 1053mm
   3840x2160     30.00*+  25.00    24.00    29.97    23.98  
   4096x2160     30.00    24.00    29.97    23.98  
   2560x1440     59.95  
   1920x1200     30.00  
   1920x1080     60.00    50.00    59.94    30.00    25.00    24.00    29.97    23.98  
   1600x1200     30.00  
   1680x1050     59.88  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94  
   720x400       70.08

The only strange thing is that amdgpu shows as both loaded and unloaded and I'm not sure if there's something conflicting there that is causing the problem... otherwise I'm not sure what I'm missing.

mrmazda · 04-07-2023, 03:05 AM

You do have the amd firmware for CPU and GPU installed, correct? Same result no matter which HDMI input you connect to, correct? Is there a TV setup option that needs a tweak? Is there an available firmware update for that new Samsung?

The author of inxi, H2 here, tried to explain to me why Display: includes gpu: amdgpu when the prior section named it as the Device. Either I didn't understand, or I've forgotten, but reading inxi output can be tricky. Nowhere is indicated that amdgpu is unloaded. The dri: subsection follows the unloaded list before gpu: amdgpu.

Just because you buy a cable that "supports 4k@60hz" is no guarantee you didn't pick one that shouldn't have passed QC. Take it back, 2 or more times if necessary and/or buy something else. Or, more carefully read the specifications. My 55" LG 4k@60hz won't do do more than 30hz from a computer either, even though hwinfo --monitor reports it's supposed to. Go figure. I don't worry about it, because my eyes aren't capable of discerning any difference. Most of what I watch is 720p or 1080i too. Find a friend to bring over a laptop or other PC or Mac and see if your TV can really do it, and what xrandr and hwinfo --monitor claim.

JamesNorris · 04-08-2023, 02:56 AM

Quote:

Originally Posted by mrmazda

You do have the amd firmware for CPU and GPU installed, correct? Same result no matter which HDMI input you connect to, correct? Is there a TV setup option that needs a tweak? Is there an available firmware update for that new Samsung?

I have checked this, and all firmware are up to date as up-to-date as Debian Testing gets, at least, and I can't see anything upstream that might affect this. TV firmware is also up-to-date.

Quote:

Originally Posted by mrmazda

The author of inxi, H2 here, tried to explain to me why Display: includes gpu: amdgpu when the prior section named it as the Device. Either I didn't understand, or I've forgotten, but reading inxi output can be tricky. Nowhere is indicated that amdgpu is unloaded. The dri: subsection follows the unloaded list before gpu: amdgpu.

Yes, oops, I misread that and overlooked the colons instead of commas.

Quote:

Originally Posted by mrmazda

Just because you buy a cable that "supports 4k@60hz" is no guarantee you didn't pick one that shouldn't have passed QC. Take it back, 2 or more times if necessary and/or buy something else. Or, more carefully read the specifications. My 55" LG 4k@60hz won't do do more than 30hz from a computer either, even though hwinfo --monitor reports it's supposed to. Go figure. I don't worry about it, because my eyes aren't capable of discerning any difference. Most of what I watch is 720p or 1080i too. Find a friend to bring over a laptop or other PC or Mac and see if your TV can really do it, and what xrandr and hwinfo --monitor claim.

Ah, yes, hwinfo --monitor shows that it does do 60hz;

Code:

45: None 00.0: 10002 LCD Monitor                                
  [Created at monitor.125]
  Unique ID: rdCR.jzNdDTD3hR0
  Parent ID: cuhJ.6G_ycjMRi84
  Hardware Class: monitor
  Model: "SAMSUNG"
  Vendor: SAM "SAMSUNG"
  Device: eisa 0x720d "SAMSUNG"
  Serial ID: "16780800"
  Resolution: 720x400@70Hz
  Resolution: 640x480@60Hz
  Resolution: 640x480@67Hz
  Resolution: 640x480@72Hz
  Resolution: 640x480@75Hz
  Resolution: 800x600@60Hz
  Resolution: 800x600@72Hz
  Resolution: 800x600@75Hz
  Resolution: 832x624@75Hz
  Resolution: 1024x768@60Hz
  Resolution: 1024x768@70Hz
  Resolution: 1024x768@75Hz
  Resolution: 1280x1024@75Hz
  Resolution: 1152x864@75Hz
  Resolution: 1280x720@60Hz
  Resolution: 1280x1024@60Hz
  Resolution: 2560x1440@60Hz
  Resolution: 3840x2160@60Hz

... but I have double-checked this by borrowing a Windows laptop and hooking up with the cables I have (which also ruled out the cable issue!) and the Windows laptop worked fine at 60hz, so definitely a Linux software/config issue somewhere.

lvm_ · 04-08-2023, 03:19 AM

Have you tried adding the missing mode yourself? https://askubuntu.com/questions/3779...tom-resolution

JamesNorris · 04-08-2023, 03:58 AM

Quote:

Originally Posted by lvm_

Have you tried adding the missing mode yourself? https://askubuntu.com/questions/3779...tom-resolution

That adds it as an option, but xrandr still shows it isn't selectable.

Code:

james@localhost:~$ cvt 3840 2160 60
# 3840x2160 59.98 Hz (CVT 8.29M9) hsync: 134.18 kHz; pclk: 712.75 MHz
Modeline "3840x2160_60.00"  712.75  3840 4160 4576 5312  2160 2163 2168 2237 -hsync +vsync

james@localhost:~$ xrandr --newmode "3840x2160_60.00"  712.75  3840 4160 4576 5312  2160 2163 2168 2237 -hsync +vsync

james@localhost:~$ xrandr --addmode HDMI-A-0 "3840x2160_60.00"

james@localhost:~$ xrandr --output HDMI-A-0 "3840x2160_60.00"
xrandr: unrecognized option '3840x2160_60.00'
Try 'xrandr --help' for more information.

If I use KDE's settings manager to set 60hz as the refresh rate it says it has changed, but still remains at 30hz according to xrandr output.

business_kid · 04-08-2023, 07:42 AM

Aside from what's been mentioned, there's a few things to check.

1. The dot clock figure in Mhz. I juist did the basic check for my screen, (1920x1080x60) and came up with dot clock = 124.42Mhz. The data for your modeline below is [Right visible]=3840 [right invisible]=4160 [left edge of left invisible]=4576`[right invisible]=5312, which is also [left visible]=0 on the next line. Ditto for the top/bottom figures. So your sum is

Code:

5312x2237x60= 712.976640 Mhz

If the maximum dot clock on your card isn't faster, it can't do that mode.

2. If your video card setup is not optimal, you're snookered. Things like insufficient pcie lanes, or a pci-4.x card on a pci-3.x bus means your setup isn't optimal.

mrmazda · 04-08-2023, 10:15 AM

More things to try:

1-override EDID via /etc/X11/xorg.con* using values you omitted from your hwinfo --monitor paste. CVT and GTF can't calculate a modeline any better than Xorg can do automatically, given appropriate values. e.g.:

Code:

# cat /etc/X11/xorg.conf.d/50-monitor.conf
Section "Monitor"
    Identifier "DefaultMonitor"
	Identifier	"DefaultMonitor"
	HorizSync	30-136
	VertRefresh	58-121
	Option	"PreferredMode"	"3840x2160"
EndSection

Adjust HorizSync and VertRefresh to the values provided by hwinfo --monitor. Tweak if necessary and you dare. If 3840x2160 alone doesn't work, try 3840x2160_60.00 or 3840x2160_59.97.

2-different distro, non-Debian-based

3-surely there must be some way to get Windows to disgorge modeline information in use

4-report a bug

JamesNorris · 04-08-2023, 02:08 PM

Quote:

Originally Posted by mrmazda

More things to try:

<snip>
2-different distro, non-Debian-based

3-surely there must be some way to get Windows to disgorge modeline information in use

So I tried a different distro, livecd with firmware, and it worked fine, so definitely a Debian issue. I have also faffed with Windows, but couldn't find anything useful (it's been 20+ years since I used Windows for anything other than work.) but I did Google in some Windows forums, and it seems that Windows sends a message to the TV to widen the input signal range, which Debian doesn't do. Some TVs recognise this signal and automatically react, and allow 50hz and 60hz rates, but others need it to be turned on in the settings.

My TV is one that switches automatically, but Debian isn't sending the message, so it isn't switching when using Linux.

I have looked through all of the settings and found something called, "Input Signal Plus" which has solved the problem after all. Strangely, this setting was in with the Bluetooth device settings, rather than the video settings, so I didn't see it before.