| Message ID | 20180913143322.77953-6-mika.westerberg@linux.intel.com |
|---|---|
| State | Accepted |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | PCI: Allow D3cold for PCIe hierarchies | expand |
On Thursday, September 13, 2018 4:33:17 PM CEST Mika Westerberg wrote: > Currently we try to keep PCIe ports runtime suspended over system > suspend if possible. This mostly happens when entering suspend-to-idle > because there is no need to re-configure wake settings. > > This causes problems if the parent port goes into D3cold and it gets > resumed upon exit from system suspend. This may happen for example if > the port is part of PCIe switch and the same switch is connected to a > PCIe endpoint that needs to be resumed. The way exit from D3cold works > according PCIe 4.0 spec 5.3.1.4.2 is that power is restored and cold > reset is signaled. After this the device is in D0unitialized state > keeping PME context if it supports wake from D3cold. > > The problem occurs when a PCIe hotplug port is left suspended and the > parent port goes into D3cold and back to D0, the port keeps its PME > context but since everything else is reset back to defaults > (D0unitialized) it is not set to detect hotplug events anymore. > > For this reason change the PCIe portdrv power management logic so that > it is fine to keep the port runtime suspended over system suspend but it > needs to be resumed upon exit to make sure it gets properly re-initialized. > > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> > --- > drivers/pci/pcie/portdrv_pci.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c > index eef22dc29140..629d5fe4c9b5 100644 > --- a/drivers/pci/pcie/portdrv_pci.c > +++ b/drivers/pci/pcie/portdrv_pci.c > @@ -109,8 +109,8 @@ static int pcie_portdrv_probe(struct pci_dev *dev, > > pci_save_state(dev); > > - dev_pm_set_driver_flags(&dev->dev, DPM_FLAG_SMART_SUSPEND | > - DPM_FLAG_LEAVE_SUSPENDED); > + dev_pm_set_driver_flags(&dev->dev, DPM_FLAG_NEVER_SKIP | > + DPM_FLAG_SMART_SUSPEND); > > if (pci_bridge_d3_possible(dev)) { > /* > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c index eef22dc29140..629d5fe4c9b5 100644 --- a/drivers/pci/pcie/portdrv_pci.c +++ b/drivers/pci/pcie/portdrv_pci.c @@ -109,8 +109,8 @@ static int pcie_portdrv_probe(struct pci_dev *dev, pci_save_state(dev); - dev_pm_set_driver_flags(&dev->dev, DPM_FLAG_SMART_SUSPEND | - DPM_FLAG_LEAVE_SUSPENDED); + dev_pm_set_driver_flags(&dev->dev, DPM_FLAG_NEVER_SKIP | + DPM_FLAG_SMART_SUSPEND); if (pci_bridge_d3_possible(dev)) { /*
Currently we try to keep PCIe ports runtime suspended over system suspend if possible. This mostly happens when entering suspend-to-idle because there is no need to re-configure wake settings. This causes problems if the parent port goes into D3cold and it gets resumed upon exit from system suspend. This may happen for example if the port is part of PCIe switch and the same switch is connected to a PCIe endpoint that needs to be resumed. The way exit from D3cold works according PCIe 4.0 spec 5.3.1.4.2 is that power is restored and cold reset is signaled. After this the device is in D0unitialized state keeping PME context if it supports wake from D3cold. The problem occurs when a PCIe hotplug port is left suspended and the parent port goes into D3cold and back to D0, the port keeps its PME context but since everything else is reset back to defaults (D0unitialized) it is not set to detect hotplug events anymore. For this reason change the PCIe portdrv power management logic so that it is fine to keep the port runtime suspended over system suspend but it needs to be resumed upon exit to make sure it gets properly re-initialized. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> --- drivers/pci/pcie/portdrv_pci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)