The many power management, thermal, and ACPI updates have been merged for the Linux 7.0 kernel. As usual there are many changes coming from fixes to new hardware support and more expansive thermal control capabilities under Linux.
On the power management front the changes include:
– Dropping the old and unused TI OMAP CPUFreq driver
– Various ARM CPUFreq driver fixes.
– The Intel Idle driver added a command line option to adjust the C-states table.
– Linux 7.0 will no longer flag the power management runtime workqueue as freezable to avoid system suspend and resume deadlocks in certain situations.
– The Intel RAPL power capping driver finally added PL4 support for aging Ice Lake processors.
– The cpupower tool now makes the installation of its systemd unit file optional.
More details on the power management changes merged for Linux 7.0 via this pull.
Over on the ACPI side, the highlights for Linux 7.0 include:
– Updating the ACPICA code against the latest upstream version that includes new ACPI 6.6 material.
– ACPI APEI updates to address excess overhead in the NMI handler.
– Various ACPI power management updates.
– Support for the Microsoft “Turn On Display” DSM to deal with select laptop issues.
More details on the ACPI updates via this pull.
Lastly are the thermal control updates for Linux 7.0:
– Support for Intel Panther Lake, Wildcat Lake, and Nova Lake processor IDs are added to the Intel TCC Cooling thermal driver.
– Support for the “slow” workload type hints on the int340x thermal driver for Intel and enabling it for Panther Lake. The new slow workload hint types for Panther Lake can be toggled using a new “workload_slow_hint_enable” attribute. The “slow” workload type hints for Panther Lake are described in the patch as:
“On processors starting from Panther Lake, additional workload type hints are provided.
The hardware analyzes workload residencies over an extended period to determine whether the workload classification tends toward idle/battery life states or sustained/performance states. Based on this long-term analysis, it classifies:
Power Classification: If the workload exhibits more idle or battery life residencies, it is classified as “power”. This is indicated by setting bit 4 of the current workload type.
Performance Classification: If the workload exhibits more sustained or performance residencies, it is classified as “performance”. This is indicated by clearing bit 4 of the current workload type.
This approach enables applications to ignore short-term workload fluctuations and instead respond to longer-term power vs. performance trends. Hints of this type are called slow workload hints.
To get notifications for slow workload hints, bit 22 in the thermal mailbox can be used for configuring workload interrupts. It is possible to exclusively enable slow workload hints or enable them in addition to the current workload hints.
To enable slow workload hints, a new sysfs attribute is added to the existing workload hint attributes.”
– Mediatek LVTS driver support for the MT7987.
Those thermal updates are outlined here.
