From: Bjorn Helgaas Date: Wed, 5 Oct 2022 02:58:08 +0000 (-0500) Subject: PCI/ASPM: Ignore L1 PM Substates if device lacks capability X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=cfc0028627cadfa271fab0290f18731193d63d87;p=linux.git PCI/ASPM: Ignore L1 PM Substates if device lacks capability 187f91db8237 ("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: 187f91db8237 ("PCI/ASPM: Remove struct aspm_register_info.l1ss_cap") Link: https://lore.kernel.org/r/20221005025809.2247547-3-helgaas@kernel.org Signed-off-by: Bjorn Helgaas Reviewed-by: Kuppuswamy Sathyanarayanan --- diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 4535228e4a64f..f12d117f44e05 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -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);