Power down Thunderbolt controllers on Macs when nothing is plugged in to save around 2W per controller.
Apple provides an ACPI-based (but nonstandard) mechanism to cut power and signal hotplug during powerdown. The usual way to implement such nonstandard mechanisms seems to be a struct dev_pm_domain. E.g. vga_switcheroo uses that for Optimus GPUs which control power with ACPI DSMs. Hence this third iteration of the series uses that as well. In v2 a more complicated approach was employed wherein power control was exerted by a PCIe port service driver instead. All the prep work went into 4.9 and 4.10, shrinking this series to just 7 patches: - The actual "meat" of the series (to borrow a term from Bjorn) is in patches [6/7] and [7/7]. These two need an ack from Andreas. - Patches [1/7] to [3/7] need an ack from Bjorn (and possibly Rafael or Mika). They're fairly small and just add a bit to struct pci_dev signifying that a device is part of a Thunderbolt daisy chain, then use that bit to modify runtime PM for PCIe ports. I'm also cc'ing Tomas and Amir at Intel Israel, if you guys have comments please shout. - Patches [4/7] and [5/7] need an ack from Rafael. Their sole purpose is to avoid a gratuitous WARN splat when assigning the struct dev_pm_domain. I've pushed the patches to GitHub to ease reviewing/fetching: https://github.com/l1k/linux/commits/thunderbolt_runpm_v3 Link to the previous iteration (v2, May 2016): http://www.spinics.net/lists/linux-pci/msg51158.html Thanks, Lukas Lukas Wunner (7): PCI: Recognize Thunderbolt devices PCI: Allow runtime PM on Thunderbolt ports PCI: Don't block runtime PM for Thunderbolt host hotplug ports Revert "PM / Runtime: Remove the exported function pm_children_suspended()" PM: Make requirements of dev_pm_domain_set() more precise thunderbolt: Power down controller when idle thunderbolt: Runtime suspend NHI when idle drivers/base/power/common.c | 15 +- drivers/base/power/runtime.c | 3 +- drivers/pci/pci.c | 20 ++- drivers/pci/pci.h | 2 + drivers/pci/probe.c | 34 +++++ drivers/thunderbolt/Kconfig | 3 +- drivers/thunderbolt/Makefile | 4 +- drivers/thunderbolt/nhi.c | 5 + drivers/thunderbolt/power.c | 356 +++++++++++++++++++++++++++++++++++++++++++ drivers/thunderbolt/power.h | 37 +++++ drivers/thunderbolt/switch.c | 9 ++ drivers/thunderbolt/tb.c | 13 ++ drivers/thunderbolt/tb.h | 2 + include/linux/pci.h | 1 + include/linux/pm_runtime.h | 7 + 15 files changed, 500 insertions(+), 11 deletions(-) create mode 100644 drivers/thunderbolt/power.c create mode 100644 drivers/thunderbolt/power.h -- 2.10.2
