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PCI: Configure ASPM when enabling device 

We can't do ASPM configuration at enumeration-time because enabling it
makes some defective hardware unresponsive, even if ASPM is disabled later
(see 41cd766b06 ("PCI: Don't enable aspm before drivers have had a chance
to veto it").  Therefore, we have to do it after a driver claims the
device.

We previously configured ASPM in pci_set_power_state(), but that's not a
very good place because it's not really related to setting the PCI device
power state, and doing it there means:

  - We incorrectly skipped ASPM config when setting a device that's
    already in D0 to D0.

  - We unnecessarily configured ASPM when setting a device to a low-power
    state (the ASPM feature only applies when the device is in D0).

  - We unnecessarily configured ASPM when called from a .resume() method
    (ASPM configuration needs to be restored during resume, but
    pci_restore_pcie_state() should already do this).

Move ASPM configuration from pci_set_power_state() to
do_pci_enable_device() so we do it when a driver enables a device.

[bhelgaas: changelog]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=79621
Fixes: db288c9c5f ("PCI / PM: restore the original behavior of pci_set_power_state()")
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Vidya Sagar <sagar.tv@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.6+
This commit is contained in:
Vidya Sagar 2014-07-16 15:33:42 +05:30 committed by Bjorn Helgaas
parent cbace46a97
commit 1f6ae47ecf
1 changed files with 6 additions and 6 deletions
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12
drivers/pci/pci.c
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@ -839,12 +839,6 @@ 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;
}
@ -1195,12 +1189,18 @@ int __weak pcibios_enable_device(struct pci_dev *dev, int bars)
static int do_pci_enable_device(struct pci_dev *dev, int bars)
{
int err;
struct pci_dev *bridge;
u16 cmd;
u8 pin;
err = pci_set_power_state(dev, PCI_D0);
if (err < 0 && err != -EIO)
return err;
bridge = pci_upstream_bridge(dev);
if (bridge)
pcie_aspm_powersave_config_link(bridge);
err = pcibios_enable_device(dev, bars);
if (err < 0)
return err;