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PCI / ACPI: Whitelist D3 for more PCIe hotplug ports

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In order to have better power management for Thunderbolt PCIe chains,
Windows enables power management for native PCIe hotplug ports if there is
the following ACPI _DSD attached to the root port:

  Name (_DSD, Package () {
      ToUUID ("6211e2c0-58a3-4af3-90e1-927a4e0c55a4"),
      Package () {
          Package () {"HotPlugSupportInD3", 1}
      }
  })

This is also documented in:

  https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-pcie-root-ports-supporting-hot-plug-in-d3

Do the same in Linux by introducing new firmware PM callback
(->bridge_d3()) and then implement it for ACPI based systems so that the
above property is checked.

There is one catch, though. The initial pci_dev->bridge_d3 is set before
the root port has ACPI companion bound (the device is not added to the PCI
bus either) so we need to look up the ACPI companion manually in that case
in acpi_pci_bridge_d3().

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Mika Westerberg 2018-09-27 16:57:14 -05:00 • committed by Bjorn Helgaas
parent 5f5e4890d5
commit 26ad34d510
4 changed files with 56 additions and 0 deletions
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9
drivers/pci/pci.c
View file

@ -793,6 +793,11 @@ static inline bool platform_pci_need_resume(struct pci_dev *dev)
return pci_platform_pm ? pci_platform_pm->need_resume(dev) : false;
}
static inline bool platform_pci_bridge_d3(struct pci_dev *dev)
{
return pci_platform_pm ? pci_platform_pm->bridge_d3(dev) : false;
}
/**
* pci_raw_set_power_state - Use PCI PM registers to set the power state of
* given PCI device
@ -2518,6 +2523,10 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
if (bridge->is_thunderbolt)
return true;
/* Platform might know better if the bridge supports D3 */
if (platform_pci_bridge_d3(bridge))
return true;
/*
* Hotplug ports handled natively by the OS were not validated
* by vendors for runtime D3 at least until 2018 because there