PCI: PCIe links may not get configured for ASPM under POWERSAVE mode (1a680b7c) · Commits · 戴 / test

v3 -> v2: Moved ASPM enabling logic to pci_set_power_state() v2 -> v1: Preserved the logic in pci_raw_set_power_state() : Added ASPM enabling logic after scanning Root Bridge : http://marc.info/?l=linux-pci&m=130046996216391&w=2 v1 : http://marc.info/?l=linux-pci&m=130013164703283&w=2 The assumption made in commit (PCI: Don't enable aspm before drivers have had a chance to veto it) that pci_enable_device() will result in re-configuring ASPM when aspm_policy is POWERSAVE is no longer valid. This is due to commit (PCI: read current power state at enable time) which resets dev->current_state to D0. Due to this the call to pcie_aspm_pm_state_change() is never made. Note the equality check (below) that returns early: ./drivers/pci/pci.c: pci_raw_set_pci_power_state() 546 /* Check if we're already there */ 547 if (dev->current_state == state) 548 return 0; Therefore OSPM never configures the PCIe links for ASPM to turn them "on". Fix it by configuring ASPM from the pci_enable_device() code path. This also allows a driver such as the e1000e networking driver a chance to disable ASPM (L0s, L1), if need be, prior to enabling the device. A driver may perform this action if the device is known to mis-behave wrt ASPM. Signed-off-by:

Naga Chumbalkar <nagananda.chumbalkar@hp.com> Acked-by:

Rafael J. Wysocki <rjw@sisk.pl> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Signed-off-by:

Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -740,6 +740,12 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)

		if (!__pci_complete_power_transition(dev, state))
		error = 0;
		/*
		* When aspm_policy is "powersave" this call ensures
		* that ASPM is configured.
		*/
		if (!error && dev->bus->self)
		pcie_aspm_powersave_config_link(dev->bus->self);

		return error;
		}

drivers/pci/pcie/aspm.c

+22 −0

Original line number	Diff line number	Diff line
		@@ -708,6 +708,28 @@ void pcie_aspm_pm_state_change(struct pci_dev *pdev)
		up_read(&pci_bus_sem);
		}

		void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
		{
		struct pcie_link_state *link = pdev->link_state;

		if (aspm_disabled \|\| !pci_is_pcie(pdev) \|\| !link)
		return;

		if (aspm_policy != POLICY_POWERSAVE)
		return;

		if ((pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
		(pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM))
		return;

		down_read(&pci_bus_sem);
		mutex_lock(&aspm_lock);
		pcie_config_aspm_path(link);
		pcie_set_clkpm(link, policy_to_clkpm_state(link));
		mutex_unlock(&aspm_lock);
		up_read(&pci_bus_sem);
		}

		/*
		* pci_disable_link_state - disable pci device's link state, so the link will
		* never enter specific states

include/linux/pci-aspm.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@
		extern void pcie_aspm_init_link_state(struct pci_dev *pdev);
		extern void pcie_aspm_exit_link_state(struct pci_dev *pdev);
		extern void pcie_aspm_pm_state_change(struct pci_dev *pdev);
		extern void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
		extern void pci_disable_link_state(struct pci_dev *pdev, int state);
		extern void pcie_clear_aspm(void);
		extern void pcie_no_aspm(void);
		@@ -39,6 +40,9 @@ static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev)
		static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev)
		{
		}
		static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
		{
		}
		static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
		{
		}

Admin message