[PATCH v5 0/4] PCI: Add support for suspending (including runtime) of PCIe ports

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Current Linux PCI core does not do any kind of power management to PCIe
ports. This means that we waste energy and consume laptop battery even if
the port has nothing connected to. These patches aim to change that to the
right direction.

Previous versions of the patches can be found below:

  v1: http://www.spinics.net/lists/linux-pci/msg49313.html
  v2: http://www.spinics.net/lists/linux-pci/msg50167.html
  v3: http://www.spinics.net/lists/linux-pci/msg50345.html
  v4: http://www.spinics.net/lists/linux-pci/msg50665.html

This assumes that recent (starting from 2015) PCIe ports are capable of
transition to D3hot/D3cold. We add a new flag to struct pci_dev 'bridge_d3'
that is set whenever the PCI core thinks the port can be put to D3. The
check in pci_pm_suspend_noirq() is then extended to cover devices where
'bridge_d3' is set.

We then add two new functions pci_bridge_d3_device_changed/removed(). These
are used to set and clear 'bridge_d3' whenever there is a change in device
power management policy (or if the device is removed). For example when
userspace forbids the device to enter D3cold pci_bridge_d3_device_changed()
will clear 'bridge_d3' of the upstream bridge.

For all PCI ports where 'bridge_d3' is set we also enable and unblock
runtime PM automatically. Only exception is when the PCIe port claims to
support hotplug. More information about that is in the changelog of
patch [4/4].

Since this also touches xhci, I'm adding Mathias and Greg to check if the
change looks reasonable.

Changes to v4:

  - Use "Put PCIe ports into D3" instead of "move" in subject and comments.

  - Add new helper function pci_power_manageable() and use it to check if
    the port can be suspended instead of open-coding it everytime.

  - Changed pci_dev_check_d3cold() to follow what Rafael suggested.

  - Dropped call to pm_runtime_mark_last_busy() in pcie_port_runtime_resume()
    as PM core does that automatically when the function returns 0.

  - Added ACKs from Rafael.

Changes to v3:

  - Make 'no_d3cold' persist for pci_dev. Once this is set through
    pci_d3cold_enable/disable(), it will persist unless changed again using
    the same functions. Those also handle setting and clearing 'bridge_d3'
    as necessary.

  - Add kernel command line parameter "pcie_port_pm=off|force" that can
    be used to forcibly disable/enable the feature.

  - Use runtime PM autosuspend instead of scheduling runtime suspend
    manually

  - Allow runtime PM always except when we are dealing with a hotplug
    bridge. Actual checking whether the port can be suspended is done in
    ->idle() and ->runtime_suspend() hooks based on 'bridge_d3'.

Changes to v2:

  - Renamed and split pci_enable_d3cold() into two functions
    pci_d3cold_enable()/disable().

  - Renamed pci_bridge_pm_update() into two functions
    pci_bridge_d3_device_changed() and pci_bridge_d3_device_removed() that
    should match better what they are doing.

  - Propagate ->bridge_d3 change to upstream bridges in
    pci_bridge_d3_update().

  - Removed pci_can_suspend() in favor of doing ->bridge_d3 check directly
    in pci_pm_suspend_noirq().

  - Extend runtime PM enabling for ports that are using native PCIe
    hotplug.

  - Call pm_runtime_no_callbacks() for PCIe port service devices (the are
    handled by the parent device).

Changes to v1:

  - Dropped patch [2/6] as there is no need to use that function from other
    files anymore.

  - Dropped patches [5-6/6] in favor of using cut-off date.

  - Updated changelog of [1/4] to mention where in the PCI core PCI bridge
    and PCIe ports are skipped from being power managed.

  - Instead of checking at suspend time if it is possible to transition the
    port to D3, do it whenever power management status of a device (below a
    port) is changed or when it is added or removed to the bus.

  - Added patch [3/4] to runtime resume a bridge when ACPI hotplug event is
    received.

Mika Westerberg (4):
  PCI: No need to set d3cold_allowed to PCIe ports
  PCI: Put PCIe ports into D3 during suspend
  ACPI / hotplug / PCI: Runtime resume bridge before rescan
  PCI: Add runtime PM support for PCIe ports

 Documentation/kernel-parameters.txt |   4 +
 drivers/pci/bus.c                   |   1 +
 drivers/pci/hotplug/acpiphp_glue.c  |   8 +-
 drivers/pci/pci-driver.c            |   5 +-
 drivers/pci/pci-sysfs.c             |   5 ++
 drivers/pci/pci.c                   | 175 ++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h                   |  11 +++
 drivers/pci/pcie/portdrv_core.c     |   2 +
 drivers/pci/pcie/portdrv_pci.c      |  51 ++++++++++-
 drivers/pci/remove.c                |   2 +
 drivers/usb/host/xhci-pci.c         |   2 +-
 include/linux/pci.h                 |   3 +
 12 files changed, 259 insertions(+), 10 deletions(-)

-- 
2.8.0.rc3