Linux 7.1 Merges AMD Dynamic EPP Fixes, Intel Bartlett Lake Scaling Fix
Merged today for Linux 7.1 was this week's power management fixes with a few notable fixes for both AMD and Intel platforms.
Last week I reported on AMD's Dynamic EPP feature for the P-State driver causing some issues for that functionality introduced during the Linux 7.1 merge window. Dynamic Energy Performance Preference (EPP) allows changing the performance profile depending upon whether the Ryzen laptop is running on AC or DC power. EPP values are dynamically adjusted based on the power state and adjust based on plug-in/out events as well as other contributing factors like the ACPI Platform Profile. The kernel is autonomously in control of setting the EPP mode and manual writes to the EPP interface for the AMD P-State driver are blocked.
Due to early bugs from the code, with today's merge Dynamic EPP is no longer offered as a Kconfig build-time option to enable but must be set via the amd_pstate=dynamic_epp=1 module parameter at boot time. Plus there are some bug fixes to this Dynamic EPP code. Hopefully soon the AMD P-State Dynamic EPP functionality will be good enough to enable by default.
On the Intel side, there are fixes to the Intel P-State driver due to it erroneously reporting a 7GHz frequency on new Bartlett Lake P-core only processors. While initially queued as a fix for Linux 7.2, the Intel P-State scaling fix was brought in as a fix for the current Linux 7.1 cycle.
In addition to that Bartlett Lake hybrid scaling factor fix, there is also a fix for the Intel P-State driver to use the correct scaling factor on Raptor Lake E CPUs too.
More details on this week's power management fixes via this pull request that was already merged to mainline.
Last week I reported on AMD's Dynamic EPP feature for the P-State driver causing some issues for that functionality introduced during the Linux 7.1 merge window. Dynamic Energy Performance Preference (EPP) allows changing the performance profile depending upon whether the Ryzen laptop is running on AC or DC power. EPP values are dynamically adjusted based on the power state and adjust based on plug-in/out events as well as other contributing factors like the ACPI Platform Profile. The kernel is autonomously in control of setting the EPP mode and manual writes to the EPP interface for the AMD P-State driver are blocked.
Due to early bugs from the code, with today's merge Dynamic EPP is no longer offered as a Kconfig build-time option to enable but must be set via the amd_pstate=dynamic_epp=1 module parameter at boot time. Plus there are some bug fixes to this Dynamic EPP code. Hopefully soon the AMD P-State Dynamic EPP functionality will be good enough to enable by default.
👁 Intel Bartlett Lake Core Series 2
On the Intel side, there are fixes to the Intel P-State driver due to it erroneously reporting a 7GHz frequency on new Bartlett Lake P-core only processors. While initially queued as a fix for Linux 7.2, the Intel P-State scaling fix was brought in as a fix for the current Linux 7.1 cycle.
In addition to that Bartlett Lake hybrid scaling factor fix, there is also a fix for the Intel P-State driver to use the correct scaling factor on Raptor Lake E CPUs too.
More details on this week's power management fixes via this pull request that was already merged to mainline.