When the operating system is booted with the default ASPM policy (POLICY_DEFAULT), current code is querying the enable/disable states from ASPM registers to determine the policy. For example, a BIOS could set the power saving state to performance and clear all ASPM control registers. A balanced ASPM policy could enable L0s and disable L1. A power conscious BIOS could enable both L0s and L1 to trade off latency and performance vs. power. After hotplug removal, pcie_aspm_exit_link_state() function clears the ASPM registers. An insertion following hotplug removal reads incorrect policy as ASPM disabled even though ASPM was enabled during boot. This is caused by the fact that same function is used for reconfiguring ASPM regardless of the power on state. ------------------------ Changes from v4 (http://www.spinics.net/lists/linux-pci/msg59245.html) ------------------------ - pci_aspm_init(): Fix function comment. Called for every device we enumerate. Upstream link partner: Shouldn't need to check pdev->link_state (should always be NULL for a brand-new device). - pcie_aspm_init_link_state(): Called for bridges (upstream end of link) after all children have been enumerated. No longer needs to check aspm_support_enabled or pdev->has_secondary_link or the VIA quirk: pci_aspm_init() already checked that stuff, so we only need to check pdev->link_state here. - split the last patch into two PCI/ASPM: move link_state cleanup to bridge remove PCI/ASPM: save power on values during bridge init - create bugzilla (https://bugzilla.kernel.org/show_bug.cgi?id=194895) - add fixes tags Sinan Kaya (4): PCI/ASPM: introduce pci_aspm_init() and add to pci_init_capabilities() PCI/ASPM: add init hook to device_add PCI/ASPM: save power on values during bridge init PCI/ASPM: move link_state cleanup to bridge remove drivers/pci/pcie/aspm.c | 93 +++++++++++++++++++++++++++++++++---------------- drivers/pci/probe.c | 3 ++ drivers/pci/remove.c | 3 +- include/linux/pci.h | 2 ++ 4 files changed, 69 insertions(+), 32 deletions(-) -- 1.9.1
