On Thursday, October 29, 2020 10:24:53 AM CET Mika Westerberg wrote:
> When a PCI bridge is runtime resumed from D3cold the underlying bus is
> walked and the attached devices are runtime resumed as well. However, in
> addition to that we also generate a wakeup event for these devices even
> though this actually is not a real wakeup event coming from the
> hardware.
>
> Normally this does not cause problems but when combined with
> /sys/power/wakeup_count like using the steps below:
>
> # count=$(cat /sys/power/wakeup_count)
> # echo $count > /sys/power/wakeup_count
> # echo mem > /sys/power/state
>
> The system suspend cycle might get aborted at this point if a PCI bridge
> that was runtime suspended (D3cold) was runtime resumed for any reason.
> The runtime resume calls pci_wakeup_bus() and that generates wakeup
> event increasing wakeup_count.
>
> Since this is not a real wakeup event we can prevent the above from
> happening by removing the call to pci_wakeup_event() in
> pci_wakeup_bus(). While there rename pci_wakeup_bus() to
> pci_resume_bus() to better reflect what it does.
>
> Reported-by: Utkarsh Patel <utkarsh.h.patel@xxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/gpu/vga/vga_switcheroo.c | 2 +-
> drivers/pci/pci.c | 16 +++++-----------
> include/linux/pci.h | 2 +-
> 3 files changed, 7 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
> index 087304b1a5d7..8843b078ad4e 100644
> --- a/drivers/gpu/vga/vga_switcheroo.c
> +++ b/drivers/gpu/vga/vga_switcheroo.c
> @@ -1039,7 +1039,7 @@ static int vga_switcheroo_runtime_resume(struct device *dev)
> mutex_lock(&vgasr_mutex);
> vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_ON);
> mutex_unlock(&vgasr_mutex);
> - pci_wakeup_bus(pdev->bus);
> + pci_resume_bus(pdev->bus);
> ret = dev->bus->pm->runtime_resume(dev);
> if (ret)
> return ret;
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 6d4d5a2f923d..b25dfa63eeb9 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1174,26 +1174,20 @@ int pci_platform_power_transition(struct pci_dev *dev, pci_power_t state)
> }
> EXPORT_SYMBOL_GPL(pci_platform_power_transition);
>
> -/**
> - * pci_wakeup - Wake up a PCI device
> - * @pci_dev: Device to handle.
> - * @ign: ignored parameter
> - */
> -static int pci_wakeup(struct pci_dev *pci_dev, void *ign)
> +static int pci_resume_one(struct pci_dev *pci_dev, void *ign)
> {
> - pci_wakeup_event(pci_dev);
> pm_request_resume(&pci_dev->dev);
> return 0;
> }
>
> /**
> - * pci_wakeup_bus - Walk given bus and wake up devices on it
> + * pci_resume_bus - Walk given bus and runtime resume devices on it
> * @bus: Top bus of the subtree to walk.
> */
> -void pci_wakeup_bus(struct pci_bus *bus)
> +void pci_resume_bus(struct pci_bus *bus)
> {
> if (bus)
> - pci_walk_bus(bus, pci_wakeup, NULL);
> + pci_walk_bus(bus, pci_resume_one, NULL);
> }
>
> static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
> @@ -1256,7 +1250,7 @@ int pci_power_up(struct pci_dev *dev)
> * may be powered on into D0uninitialized state, resume them to
> * give them a chance to suspend again
> */
> - pci_wakeup_bus(dev->subordinate);
> + pci_resume_bus(dev->subordinate);
> }
>
> return pci_raw_set_power_state(dev, PCI_D0);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 22207a79762c..9256ef2e4327 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1271,7 +1271,7 @@ bool pci_dev_run_wake(struct pci_dev *dev);
> void pci_d3cold_enable(struct pci_dev *dev);
> void pci_d3cold_disable(struct pci_dev *dev);
> bool pcie_relaxed_ordering_enabled(struct pci_dev *dev);
> -void pci_wakeup_bus(struct pci_bus *bus);
> +void pci_resume_bus(struct pci_bus *bus);
> void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state);
>
> /* For use by arch with custom probe code */
>
