Bug 444298

How do you measure the frame rate? and what do you expect to see

> OBSERVED RESULT
> Nothing Happens

(In reply to Vlad Zahorodnii from comment #1)
> How do you measure the frame rate? and what do you expect to see
> 
> > OBSERVED RESULT
> > Nothing Happens

Easiest way for me is to simply look at the Monitor OSD
For example the currently the display info shows the following:
Model
Input
Current: 2560x1440, 200Hz
Maximum: 2560x1440, 240Hz.

Every refresh rate changes the current (if I choose 144hz the current will change) except 240hz which does nothing at all.

It might be a bandwidth limitation. Can you please check wayland session logs after changing the refresh rate? the logs can be found at ~/.local/share/sddm/wayland-session.log (please remove any sensitive information before attaching it to the bug report)

Also, it will be helpful to have the output of `drm_info` (https://github.com/ascent12/drm_info). Most distros don't ship it, you would need to build it from source code or install from AUR if you use Arch. `drm_info` will print the actual mode set by kwin.

Created attachment 142858 [details]
drm_info as requested

Created attachment 142859 [details]
wayland-session.log

(In reply to Vlad Zahorodnii from comment #3)
> It might be a bandwidth limitation. Can you please check wayland session
> logs after changing the refresh rate? the logs can be found at
> ~/.local/share/sddm/wayland-session.log (please remove any sensitive
> information before attaching it to the bug report)
> 
> Also, it will be helpful to have the output of `drm_info`
> (https://github.com/ascent12/drm_info). Most distros don't ship it, you
> would need to build it from source code or install from AUR if you use Arch.
> `drm_info` will print the actual mode set by kwin.

I've done just that.

Based on drm_info output

│   ├───CRTC 0
│   │   ├───Object ID: 53
│   │   ├───Mode: 2560x1440@199.99 driver phsync nvsync
│   │   ├───Gamma size: 256
│   │   └───Properties
│   │       ├───"ACTIVE" (atomic): range [0, 1] = 1
│   │       ├───"MODE_ID" (atomic): blob = 114
│   │       │   └───2560x1440@199.99 driver phsync nvsync


and wayland session log

  kwin_wayland_drm: crtc 53
  kwin_wayland_drm: 	"MODE_ID": 114->108

it indeed looks like kwin tries to change the mode with refresh rate of 199.99Hz to (I guess) 244Hz, but the atomic test only commit fails (perhaps due to bandwidth limitation?). Can you try unplugging the other output?

Another thing that's worth testing is whether it's due to kwin not using modifiers. Can you add

  KWIN_DRM_USE_MODIFIERS=1

to your /etc/environment and reboot the computer?

(In reply to Vlad Zahorodnii from comment #7)
> Based on drm_info output
> 
> │   ├───CRTC 0
> │   │   ├───Object ID: 53
> │   │   ├───Mode: 2560x1440@199.99 driver phsync nvsync
> │   │   ├───Gamma size: 256
> │   │   └───Properties
> │   │       ├───"ACTIVE" (atomic): range [0, 1] = 1
> │   │       ├───"MODE_ID" (atomic): blob = 114
> │   │       │   └───2560x1440@199.99 driver phsync nvsync
> 
> 
> and wayland session log
> 
>   kwin_wayland_drm: crtc 53
>   kwin_wayland_drm: 	"MODE_ID": 114->108
> 
> it indeed looks like kwin tries to change the mode with refresh rate of
> 199.99Hz to (I guess) 244Hz, but the atomic test only commit fails (perhaps
> due to bandwidth limitation?). Can you try unplugging the other output?

Disconnecting the second monitor alone doesn't work, I was able to get it to work after disconnecting the second monitor and restarting then setting it to 240hz.

I guess its as you say, a bandwidth limitation, i'm running an RX580 on the PCIE16X_3 slot on the asus x570 dark hero which for some odd reason defaults to x4 according to the bios.

Have you tried setting KWIN_DRM_USE_MODIFIERS to 1? This may result in framebuffers having compressed modifier, which is good in terms of bandwidth.

(In reply to Vlad Zahorodnii from comment #10)
> Have you tried setting KWIN_DRM_USE_MODIFIERS to 1? This may result in
> framebuffers having compressed modifier, which is good in terms of bandwidth.

Yea I tried that but it absolutely didn't do anything. (I just added it to the environment file directly as written, unless there is something else I need to do)

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!

Hi, I have been having the same issue. I have a 2560x1440@240hz monitor, which KDE limits to 144hz. It may be a bandwidth issue, but it would be good for KDE to show that rather than showing a 'successful' switch to 240hz until I click out and back into the displays page.

We unfortunately don't have enough information to show anything more than "failed", but we should at least show that

This is fixed in Plasma 6.3, with https://invent.kde.org/plasma/kscreen/-/merge_requests/329