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**Summary:**
On Ubuntu 24.04, my AMD Cezanne integrated GPU (Radeon Vega) cannot drive my
monitor at 2560x1440 @ 240Hz. The highest working refresh rate is 144Hz. On
Linux Mint 21.3 with an older kernel and Mesa, 2560x1440 @ 240Hz works
perfectly.
**System details:**
- Motherboard: ASUS ROG STRIX B550-F GAMING WIFI
- BIOS version: 3621
- GPU: AMD Cezanne [Radeon Vega Series / Radeon Vega Mobile Series] (iGPU only,
no PCIe GPU)
- Kernel version (Ubuntu 24.04): 6.14.0-29-generic
- Kernel driver in use: amdgpu
**What works:**
- On Mint 21.3, running kernel 5.15 and Mesa 21.3, 2560x1440 @ 240Hz works
correctly.
**What fails:**
- On Ubuntu 24.04 with kernel 6.14 and Mesa 24.x, the display fails to run at
240Hz.
- It only works up to 144Hz.
- This indicates a regression in kernel or Mesa between these versions.
**Steps to reproduce:**
1. Boot Ubuntu 24.04 with AMD Cezanne iGPU.
2. Connect monitor capable of 2560x1440 @ 240Hz over DisplayPort.
3. Attempt to set resolution/refresh to 2560x1440 @ 240Hz using `xrandr` or
Display Settings.
4. Screen flickers or reverts back to 144Hz.
**Additional debug info:**
I have attached a full debug archive containing:
- `dmesg` with `drm.debug=0x1e`
- EDID dump
- `xrandr --verbose`
- `lspci -nnk`
- Mesa package version comparisons (Mint vs Ubuntu 24.04)
- Kernel command line
- `/sys/class/drm/` details
Hardware
Motherboard: ASUS ROG Strix B550-F Gaming WiFi
BIOS Version: 3621
GPU: AMD Cezanne [Radeon Vega Series / Mobile] (iGPU only, no discrete
GPU)
PCI ID: 1002:1638
Monitor: 2560x1440 @ 240Hz, connected via DisplayPort
Software
Ubuntu 24.04 Kernel (failing): 6.14.0-29-generic
Linux Mint 21.3 Kernel (working): 5.15.0-153-generic
Mesa versions included in logs:
Mint 21.3 (working): 23.2.1-1ubuntu3.1~22.04.3
Ubuntu 24.04 (failing): 24.0.x (exact packages in logs)
Steps to Reproduce
Boot Ubuntu 24.04 with the default kernel.
Connect monitor via DisplayPort.
Attempt to set display mode:
xrandr --output DP-1 --mode 2560x1440 --rate 240
Here’s the **exact bug description** you can copy and paste into
Launchpad:
---
### **Summary**
Display fails to set 2560x1440 @ 240Hz on Ubuntu 24.04 with AMD Cezanne iGPU
(Vega).
The same hardware works perfectly on Linux Mint 21.3.
---
### **Hardware**
* **Motherboard:** ASUS ROG Strix B550-F Gaming WiFi
* **BIOS Version:** 3621
* **GPU:** AMD Cezanne \[Radeon Vega Series / Mobile] (iGPU only, no discrete
GPU)
* PCI ID: `1002:1638`
* **Monitor:** 2560x1440 @ 240Hz, connected via DisplayPort
---
### **Software**
* **Ubuntu 24.04 Kernel (failing):** 6.14.0-29-generic
* **Linux Mint 21.3 Kernel (working):** 5.15.0-153-generic
* **Mesa versions included in logs:**
* Mint 21.3 (working): 23.2.1-1ubuntu3.1\~22.04.3
* Ubuntu 24.04 (failing): 24.0.x (exact packages in logs)
---
### **Steps to Reproduce**
1. Boot Ubuntu 24.04 with the default kernel.
2. Connect monitor via DisplayPort.
3. Attempt to set display mode:
```bash
xrandr --output DP-1 --mode 2560x1440 --rate 240
```
4. **Expected result:** Monitor switches to 2560x1440 @ 240Hz and works
normally.
5. **Actual result:** Command does nothing, no error output, and resolution
remains at 60Hz.
---
### **Additional Notes**
* Same exact hardware, cable, and monitor works fine on Linux Mint 21.3 (Kernel
5.15).
* Kernel parameter `amdgpu.dc=0` was tested but resulted in a black screen.
* This suggests a regression either in the kernel's AMDGPU driver or related
Mesa components between these versions.
---
### **Logs and Data**
A complete log bundle is attached as **`amdgpu-bug.tar.gz`**,
containing:
* `dmesg-drm.txt` – full dmesg with `drm.debug=0x1f`
* `drm-debug-6.14.0-29-generic.log.gz` – raw compressed kernel log
* `mesa-packages21.3.txt.gz` and `mesa-packages24.04.txt.gz` – Mesa package
versions
* `lspci-nnk.txt` – full PCI listing
* `xrandr-verbose.txt` – full xrandr output
* `proc-cmdline.txt`, `uname.txt`, `dmidecode.txt`
* `dp-link_settings.txt` and `sys-class-drm.txt` – connector info
Please see the attached archive for all relevant diagnostic information.
---
### **Impact**
* Ubuntu 24.04 cannot drive a 2560x1440 @ 240Hz display on AMD Cezanne Vega
iGPU, while Linux Mint 21.3 can.
* This impacts gaming and high refresh rate workflows on Ubuntu.
Please see `amdgpu-bug.tar.gz` attached for full logs.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: bot-comment
--
Cezanne iGPU: 2560x1440@240Hz fails on Ubuntu 24.04 (works on Mint 21.3)
https://bugs.launchpad.net/bugs/2125234
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