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PCI/ASPM: Do not initialize link state when aspm_disabled is set
authorPatrick Talbert <ptalbert@redhat.com>
Wed, 5 Sep 2018 07:12:53 +0000 (09:12 +0200)
committerBjorn Helgaas <bhelgaas@google.com>
Tue, 18 Sep 2018 21:19:06 +0000 (16:19 -0500)
commit17c91487364fb33797ed84022564ee7544ac4945
tree3bd784b7eee102e171b50b21e4e16dbe133ea6b3
parentc238252f86c1833fc0cbee3ce3b4c295d3ab24ef
PCI/ASPM: Do not initialize link state when aspm_disabled is set

Now that ASPM is configured for *all* PCIe devices at boot, a problem is
seen with systems that set the FADT NO_ASPM bit.  This bit indicates that
the OS should not alter the ASPM state, but when
pcie_aspm_init_link_state() runs it only checks for !aspm_support_enabled.
This misses the ACPI_FADT_NO_ASPM case because that is setting
aspm_disabled.

The result is systems may hang at boot after 1302fcf; avoidable if they
boot with pcie_aspm=off (sets !aspm_support_enabled).

Fix this by having aspm_init_link_state() check for either
!aspm_support_enabled or acpm_disabled.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=201001
Fixes: 1302fcf0d03e ("PCI: Configure *all* devices, not just hot-added ones")
Signed-off-by: Patrick Talbert <ptalbert@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
drivers/pci/pcie/aspm.c