Hi Sinan

Hi Mayurkumkar,

On 3/25/2017 5:38 PM, Sinan Kaya wrote:

quoted

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(-)

Can you test this on your system and provide your tested-by if all good?

Sinan

Thanks for your patches. I am seeing kernel panic after applying
these patches (on top of latest kernel) each time during early boot in pci_aspm_init() (any hints already?) function.
Need to check if it's something related to my local setup or it's because of these changes.
For now I don't have more details why it crashes but I will dig in further and I will provide
you more data as soon as I have it.

--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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