v2 -> v1:
. Kept the logic in pci_raw_set_power_state
. Changed the ASPM enabling logic
. Modified the text that describes the problem
v1 : http://marc.info/?l=linux-pci&m=130013164703283&w=2
The assumption made in commit 41cd766b065970ff6f6c89dd1cf55fa706c84a3d
(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POWERSAVE is no longer valid.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
97c145f7c87453cec90e91238fba5fe2c1561b32 (PCI: read current power state
at enable time) which resets dev->current_state to D0. This makes the
equality check (below) become true, so pcie_aspm_pm_state_change() never
546 /* Check if we're already there */
547 if (dev->current_state == state)
548 return 0;
So OSPM doesnn't configure the PCIe links for ASPM.
The patch below does the following:
At the end of each Root Bridge scan make a call to configure ASPM when the
ASPM policy is set to "powersave" mode. Note that if a previous pass had
completed the configuration for all devices under that Bridge then the
configuration will not take place again because pcie_config_aspm_link()
checks to see if the link is already in the requested state.
We won't reconfigure ASPM when _OSC control is not granted.