Commit 66ff14e5 authored May 06, 2020 by Kai-Heng Feng Committed by Bjorn Helgaas May 07, 2020

PCI/ASPM: Allow ASPM on links to PCIe-to-PCI/PCI-X Bridges

7d715a6c ("PCI: add PCI Express ASPM support") added the ability for
Linux to enable ASPM, but for some undocumented reason, it didn't enable
ASPM on links where the downstream component is a PCIe-to-PCI/PCI-X Bridge.

Remove this exclusion so we can enable ASPM on these links.

The Dell OptiPlex 7080 mentioned in the bugzilla has a TI XIO2001
PCIe-to-PCI Bridge.  Enabling ASPM on the link leading to it allows the
Intel SoC to enter deeper Package C-states, which is a significant power
savings.

[bhelgaas: commit log]
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207571
Link: https://lore.kernel.org/r/20200505173423.26968-1-kai.heng.feng@canonical.com


Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

parent 8f3d9f35

drivers/pci/pcie/aspm.c

+0 −10

Original line number	Diff line number	Diff line
		@@ -628,16 +628,6 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)

		/* Setup initial capable state. Will be updated later */
		link->aspm_capable = link->aspm_support;
		/*
		* If the downstream component has pci bridge function, don't
		* do ASPM for now.
		*/
		list_for_each_entry(child, &linkbus->devices, bus_list) {
		if (pci_pcie_type(child) == PCI_EXP_TYPE_PCI_BRIDGE) {
		link->aspm_disable = ASPM_STATE_ALL;
		break;
		}
		}

		/* Get and check endpoint acceptable latencies */
		list_for_each_entry(child, &linkbus->devices, bus_list) {

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