y (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 of the power on state. ------------------------ Changes from v3 (https://lkml.org/lkml/2017/3/8/670) ------------------------ - call pcie_aspm_init_link_state() for every device, maybe from pci_init_capabilities() - for bridges, have pcie_aspm_init_link_state() allocate a link_state, regardless of whether it currently has any children, and save the ASPM settings done by firmware - for endpoints, have pcie_aspm_init_link_state() do the actual ASPM setup of the link as it currently does - for endpoints, change pcie_aspm_exit_link_state() so it cleans up the device's own state and disables ASPM if necessary, but doesn't remove the parent's link_state - for bridges, change pcie_aspm_exit_link_state() so it frees the bridge's own link_state Sinan Kaya (3): PCI/ASPM: divide ASPM capability init into pre and post init PCI/ASPM: move part of ASPM initialization to pci_init_capabilities PCI/ASPM: move link_state cleanup to bridge remove drivers/pci/pcie/aspm.c | 175 +++++++++++++++++++++++++++++++++++------------- drivers/pci/probe.c | 3 + include/linux/pci.h | 6 ++ 3 files changed, 136 insertions(+), 48 deletions(-) -- 1.9.1
