https://bugs.kde.org/show_bug.cgi?id=522776
Bug ID: 522776
Summary: AMDGPU memory clock sensor reports 0 MHz when
pp_dpm_mclk has no active "*" entry (RX 7900 XTX)
Classification: Frameworks and Libraries
Product: ksystemstats
Version First 6.4.0
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: General
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Summary
On an AMD Radeon RX 7900 XTX (Navi31), the Plasma System Monitor memory clock
sensor correctly reports 772 MHz while idle, but reports 0 MHz whenever the
VRAM reaches its highest performance state.
The kernel, hwmon, amdgpu_top and lm_sensors all report the correct frequency.
This appears to be caused by ksystemstats parsing pp_dpm_mclk and expecting an
active * entry, which disappears in the highest memory DPM state.
Software Versions
Plasma: 6.7.2
ksystemstats: 6.7.2
Kernel: (paste output of uname -r)
Mesa: (paste output of glxinfo -B | grep "OpenGL version")
GPU:
Sapphire RX 7900 XTX Vapor-X
Steps to reproduce
Add the "GPU Memory Frequency" sensor to a Plasma widget.
Observe the value while the GPU is idle.
Run a GPU-intensive workload.
Observe the sensor.
Expected result
The sensor should display the actual memory frequency.
For example:
772 MHz
↓
1300 MHz
(or the corresponding effective value depending on how the sensor is defined).
Actual result
The sensor changes from
772 MHz
to
0 MHz
while the GPU is under load.
Evidence
The Plasma sensor reports:
Idle
gdbus ... sensorData ['gpu/gpu0/memoryFrequency']
772
Load
gdbus ... sensorData ['gpu/gpu0/memoryFrequency']
0
However, the driver reports:
Idle
cat /sys/class/drm/card1/device/pp_dpm_mclk
0: 96Mhz
1: 456Mhz
2: 772Mhz *
3: 1249Mhz
Load
0: 96Mhz
1: 456Mhz
2: 772Mhz
3: 1249Mhz
Notice that the active * disappears completely.
The actual memory clock is still reported correctly by:
amdgpu_top
lm_sensors
/sys/kernel/debug/dri/1/amdgpu_pm_info
Therefore the driver is functioning correctly and only the ksystemstats sensor
returns 0.
It looks like the AMD backend assumes that one DPM state is always marked with
*, which is not true on this GPU.
A more reliable source may be:
/sys/class/drm/card1/device/hwmon/.../freq2_input
which is what lm_sensors reads.
SOFTWARE/OS VERSIONS
Operating System (available in the Info Center app, or by running `kinfo` in a
terminal window):
Operating System: Arch Linux
KDE Plasma Version: 6.7.2
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
Kernel Version: 7.1.3-1-cachyos-bore (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 32 GiB of RAM (31.2 GiB usable)
Graphics Processor: AMD Radeon RX 7900 XTX
ADDITIONAL INFORMATION
Linux Ry 7.1.3-1-cachyos-bore #1 SMP PREEMPT_DYNAMIC Mon, 06 Jul 2026 17:33:12
+0000 x86_64 GNU/Linux
ksystemstats 6.7.2-1
plasma-systemmonitor 6.7.2-1
mesa-git 26.2.0_devel.223596.f1c30d65e15.d41d8cd-1
linux 7.1.2.arch3-1
linux-firmware 20260622-1
cat /sys/class/drm/card1/device/pp_dpm_mclk
0: 96Mhz
1: 456Mhz
2: 772Mhz *
3: 1249Mhz
gdbus call --session \
--dest org.kde.ksystemstats1 \
--object-path /org/kde/ksystemstats1 \
--method org.kde.ksystemstats1.sensorData \
"['gpu/gpu0/memoryFrequency']"
([('gpu/gpu0/memoryFrequency', <772>)],)
When memory is up to 2600mhz:
cat /sys/class/drm/card1/device/pp_dpm_mclk
0: 96Mhz
1: 456Mhz
2: 772Mhz
3: 1249Mhz
gdbus call --session \
--dest org.kde.ksystemstats1 \
--object-path /org/kde/ksystemstats1 \
--method org.kde.ksystemstats1.sensorData \
"['gpu/gpu0/memoryFrequency']"
([('gpu/gpu0/memoryFrequency', <0>)],)
I have confirmed that this is not a widget issue. The widget simply displays
the value returned by org.kde.ksystemstats1.sensorData, which itself changes
from 772 to 0 under load.
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