Re: [PATCH v2 00/10] PCI: Allow D3cold for PCIe hierarchies

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On Thu, Sep 13, 2018 at 05:33:12PM +0300, Mika Westerberg wrote:
> Hi all,
> 
> This patch series aims to allow PCIe hierarchies enter D3cold both during
> system sleep and runtime, including PCIe hotplug ports.
> 
> The motivation of this series are recent systems such as Lenovo Thinkpad X1
> Carbon 6th gen and upcoming Dell laptops where the Thunderbolt controller
> is always present in the system (pretty much like what Apple systems have
> been doing for years). Because it is always present it consumes energy so
> it is important to power it off when idle.
> 
> The PCIe root port hosting the Thunderbolt controller and all the connected
> external PCIe devices includes a standard ACPI power resource and related
> methods _PR3, _PR0, _PRW and _DSW that take care of the actual transition
> to D3cold and back to D0.
> 
> With current kernels entering system sleep states leaves the root port into
> D3hot which means the ACPI power resource is still on. This is bad when
> system enters suspend-to-idle (all these systems are s2idle only) because
> the BIOS is not involved and the devices are effectively left on, consuming
> battery unnecessarily.
> 
> Patches 1-4 add D3cold support for system sleep and the subsequent patches
> do the same for runtime PM.
> 
> In case someone wants to try out runtime PM, the xHCI controller that is
> part of the PCIe switch below the root port needs to have runtime PM
> "unblocked" manually (this will be automatic in future).
> 
> For Thinkpad:
> 
>   # echo auto > /sys/bus/pci/devices/0000:3b:00.0/power/control
> 
> For Dell:
> 
>   # echo auto > /sys/bus/pci/devices/0000:39:00.0/power/control
> 
> Note if the root port enters D3cold, running things like 'lspci' brings it
> back t0 D0 (because PCI config space is not accessible in D3cold) so if one
> wants to check out the power state without accidentally bringing the device
> back into D0 needs to do that indirectly. If the root port is 1d.0 power
> state can be checked:
> 
>   # cat /sys/bus/pci/devices/0000:00:1d.0/power/runtime_status
>   suspended
>   # cat /sys/bus/pci/devices/0000:00:1d.0/firmware_node/real_power_state
>   D3cold
> 
> Even if this again revolves around Thunderbolt I think these apply to any
> PCIe system supporting D3cold.
> 
> These patches apply on top of pci.git pci/hotplug. The previus version of
> the series can be viewed here:
> 
>   https://www.spinics.net/lists/linux-acpi/msg83841.html
> 
> Changes from v1:
> 
>   * Updated comment in patch [1/10] according what Rafael suggested
>   * Added empty line in patch [2/10]
>   * Check for !pciehp_poll_mode in [4/10]
>   * Use DPM_FLAG_NEVER_SKIP instead of DPM_FLAG_SMART_PREPARE which
>     simplifies patch [5/10] signicantly 
>   * Use const in acpi_data_get_property() and change int -> unsigned int
>     in patch [9/10]
>   * Added tags 
> 
> Mika Westerberg (10):
>   PCI: Do not skip power managed bridges in pci_enable_wake()
>   PCI / ACPI: Enable wake automatically for power managed bridges
>   PCI: pciehp: Disable hotplug interrupt during suspend
>   PCI: pciehp: Do not handle events if interrupts are masked
>   PCI: portdrv: Resume upon exit from system suspend if left runtime suspended
>   PCI: portdrv: Add runtime PM hooks for port service drivers
>   PCI: pciehp: Implement runtime PM callbacks
>   PCI/PME: Implement runtime PM callbacks
>   ACPI / property: Allow multiple property compatible _DSD entries
>   PCI / ACPI: Whitelist D3 for more PCIe hotplug ports
> 
>  drivers/acpi/property.c           | 97 ++++++++++++++++++++++---------
>  drivers/acpi/x86/apple.c          |  2 +-
>  drivers/gpio/gpiolib-acpi.c       |  2 +-
>  drivers/pci/hotplug/pciehp.h      |  2 +
>  drivers/pci/hotplug/pciehp_core.c | 37 ++++++++++++
>  drivers/pci/hotplug/pciehp_hpc.c  | 16 ++++-
>  drivers/pci/pci-acpi.c            | 57 +++++++++++++++++-
>  drivers/pci/pci.c                 | 18 +++++-
>  drivers/pci/pci.h                 |  3 +
>  drivers/pci/pcie/pme.c            | 27 +++++++++
>  drivers/pci/pcie/portdrv.h        |  4 ++
>  drivers/pci/pcie/portdrv_core.c   | 20 +++++++
>  drivers/pci/pcie/portdrv_pci.c    | 14 ++---
>  include/acpi/acpi_bus.h           |  8 ++-
>  include/linux/acpi.h              |  9 +++
>  15 files changed, 273 insertions(+), 43 deletions(-)

Applied the whole series (not just 01/10, which I applied by itself for
some reason) to pci/hotplug for v4.20, thanks!



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