There's an xHC device that doesn't wake when a USB device gets plugged to its USB port. The driver's own runtime suspend callback was called, PME signaling was enabled, but it stays at PCI D0. A PCI device can be runtime suspended to D0 when it supports D0 PME and its _S0W reports D0. Theoratically this should work, but as [1] specifies, D0 doesn't have wakeup capability. To avoid this problematic situation, we should avoid runtime suspend if D0 is the only state that can wake up the device. [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/kernel/device-working-state-d0 Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> --- drivers/pci/pci-driver.c | 5 +++++ drivers/pci/pci.c | 2 +- include/linux/pci.h | 3 +++ 3 files changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index cae630fe6387..15a6310c5d7b 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1251,6 +1251,11 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; } + if (pci_target_state(pci_dev, device_can_wakeup(dev)) == PCI_D0) { + dev_dbg(dev, "D0 doesn't have wakeup capability\n"); + return -EBUSY; + } + pci_dev->state_saved = false; if (pm && pm->runtime_suspend) { error = pm->runtime_suspend(dev); diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 8abc843b1615..ceee6efbbcfe 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2294,7 +2294,7 @@ EXPORT_SYMBOL(pci_wake_from_d3); * If the platform can't manage @dev, return the deepest state from which it * can generate wake events, based on any available PME info. */ -static pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup) +pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup) { pci_power_t target_state = PCI_D3hot; diff --git a/include/linux/pci.h b/include/linux/pci.h index 4a5a84d7bdd4..91e8dc4d04aa 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1188,6 +1188,7 @@ bool pci_pme_capable(struct pci_dev *dev, pci_power_t state); void pci_pme_active(struct pci_dev *dev, bool enable); int pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable); int pci_wake_from_d3(struct pci_dev *dev, bool enable); +pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup); int pci_prepare_to_sleep(struct pci_dev *dev); int pci_back_from_sleep(struct pci_dev *dev); bool pci_dev_run_wake(struct pci_dev *dev); @@ -1672,6 +1673,8 @@ static inline int pci_set_power_state(struct pci_dev *dev, pci_power_t state) { return 0; } static inline int pci_wake_from_d3(struct pci_dev *dev, bool enable) { return 0; } +pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup) +{ return PCI_D0; } static inline pci_power_t pci_choose_state(struct pci_dev *dev, pm_message_t state) { return PCI_D0; } -- 2.17.1
