The upcoming Linux 5.5 kernel cycle should bring an improvement for power management on Intel’s latest-generation Ice Lake processors.
With my Dell XPS 7390 Ice Lake Core i7 testing the power management has been quite good, but it looks like Linux 5.5 will be even better. On Saturday this commit was staged as part of USB testing code ahead of the upcoming Linux 5.5 merge window.
Intel’s Mika Westerberg who is known for his maintaining of Thunderbolt code and other contributions explained in the commit, “Intel Ice Lake has two xHCI controllers one on PCH and the other as part of the CPU itself. The latter is also part of the so called Type C Subsystem (TCSS) sharing ACPI power resources with the PCIe root ports and the Thunderbolt controllers. In order to put the whole TCSS block into D3cold the xHCI needs to be runtime suspended as well when idle. For this reason allow runtime PM as default for Ice Lake TCSS xHCI controller.“
It’s quite a simple change so might also end up being queued for back-porting to current Linux stable series. No power management numbers were provided but considering that this change is needed for putting the whole TCSS block into D3cold state during idle, it should be a positive improvement. With time, of course, I’ll have my own power numbers for my Dell XPS 7390 on this forthcoming kernel.
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