Re: [PATCH v2 05/10] PCI: portdrv: Resume upon exit from system suspend if left runtime suspended

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

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>