Commit cfc00286 authored by Bjorn Helgaas's avatar Bjorn Helgaas
Browse files

PCI/ASPM: Ignore L1 PM Substates if device lacks capability 

187f91db ("PCI/ASPM: Remove struct aspm_register_info.l1ss_cap")
inadvertently removed a check for existence of the L1 PM Substates (L1SS)
Capability before reading it.

If there is no L1SS Capability, this means we mistakenly read PCI_COMMAND
and PCI_STATUS (config address 0x04) and interpret that as the PCI_L1SS_CAP
register, so we may incorrectly configure L1SS.

Make sure the L1SS Capability exists before trying to read it.

Fixes: 187f91db ("PCI/ASPM: Remove struct aspm_register_info.l1ss_cap")
Link: https://lore.kernel.org/r/20221005025809.2247547-3-helgaas@kernel.org


Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
parent 9e2a0317

drivers/pci/pcie/aspm.c

+3 −0
Original line number Diff line number Diff line
@@ -560,6 +560,9 @@ static void aspm_l1ss_init(struct pcie_link_state *link) 
	u32 parent_l1ss_cap, child_l1ss_cap;

	u32 parent_l1ss_ctl1 = 0, child_l1ss_ctl1 = 0;



	if (!parent->l1ss || !child->l1ss)

		return;



	/* Setup L1 substate */

	pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CAP,

			      &parent_l1ss_cap);