** Changed in: linux-oem-5.17 (Ubuntu)
Status: Fix Committed => Invalid
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https://bugs.launchpad.net/bugs/1956509
Title:
Support AMD P-State cpufreq control mechanism
Status in HWE Next:
New
Status in linux package in Ubuntu:
In Progress
Status in linux-oem-5.14 package in Ubuntu:
Invalid
Status in linux-oem-5.17 package in Ubuntu:
Invalid
Status in linux source package in Focal:
Invalid
Status in linux-oem-5.14 source package in Focal:
Fix Released
Status in linux-oem-5.17 source package in Focal:
Invalid
Status in linux source package in Jammy:
In Progress
Status in linux-oem-5.14 source package in Jammy:
Invalid
Status in linux-oem-5.17 source package in Jammy:
Fix Released
Bug description:
[SRU Justification]
[Impact]
AMD P-State CPU performance scaling driver not yet supported on AMD Zen
based CPU series.
[Fix]
Mainline commits starting at commit d341db8f48ea ("x86/cpufeatures: Add
AMD Collaborative Processor Performance Control feature flag") from v5.17.
Even this committed, the defconfig will build it as module, and that
prevents AMD P-State driver from actually taking effect. Therefore an
additional fix to the kernel configs is necessary.
[Test Case]
$ sudo cpupower frequency-info
analyzing CPU 0:
driver: amd-pstate
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 131 us
hardware limits: 400 MHz - 3.10 GHz
available cpufreq governors: conservative ondemand userspace powersave
performance schedutil
current policy: frequency should be within 1.60 GHz and 3.10 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency: Unable to call hardware
current CPU frequency: 1.59 GHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: yes
Boost States: 0
Total States: 3
Pstate-P0: 3100MHz
Pstate-P1: 1800MHz
Pstate-P2: 1600MHz
[Where problems could occur]
The CPPC feature is implemented in two ways depending on underlying HW
details for the APU/CPU:
* Dedicated MSR
* Shared memory
The metrics used to measure power/performance efficiency don't show any
improvement on the designs that use shared memory. They do show
improvements in the MSR designs.
So the code will only enable it by default on the MSR implementation.
[Other Info]
Althought the v5.17 kernel and newer should have already this committed,
an additional fix to the kernel configs is necessary, and
unstable/oem-5.17 are also nominated (in a separate thread for they don't
need other parts but the config).
========== original bug report ==========
https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-
pm.git/commit/?h=linux-
next&id=40181d67f1e9f1ac87af9c0c194e40ab2a081974
$ sudo cpupower frequency-info
analyzing CPU 0:
driver: amd-pstate
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 131 us
hardware limits: 400 MHz - 3.10 GHz
available cpufreq governors: conservative ondemand userspace powersave
performance schedutil
current policy: frequency should be within 1.60 GHz and 3.10 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency: Unable to call hardware
current CPU frequency: 1.59 GHz (asserted by call to kernel)
boost state support:
Supported: yes
Active: yes
Boost States: 0
Total States: 3
Pstate-P0: 3100MHz
Pstate-P1: 1800MHz
Pstate-P2: 1600MHz
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