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PCI: PCIe links may not get configured for ASPM under POWERSAVE mode 

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 41cd766b06
(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POWERSAVE is no longer valid.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
97c145f7c8 (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>
This commit is contained in:
Naga Chumbalkar 2011-03-21 03:29:08 +00:00 committed by Jesse Barnes
parent 8b8bae901c
commit 1a680b7c32
3 changed files with 32 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/pci/pci.c
View File

@ -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;
}

22
drivers/pci/pcie/aspm.c
View File

@ -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

4
include/linux/pci-aspm.h
View File

@ -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)
{
}