According to PCI Express Base Specification Revision 6.0, Section 5.5.4: "If setting either or both of the enable bits for PCI-PM L1 PM Substates, both ports must be configured as described in this section while in D0." Add notes into pci_enable_link_state(_locked) for kernel-doc. Hope these notify callers ensuring the devices in D0, if PCI-PM L1 PM Substates are going to be enabled. Signed-off-by: Jian-Hong Pan <jhp@xxxxxxxxxxxxx> --- v3: - Fix as readable comments drivers/pci/pcie/aspm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 7f1d674ff171..a39d2ee744cb 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1416,6 +1416,9 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) * touch the LNKCTL register. Also note that this does not enable states * disabled by pci_disable_link_state(). Return 0 or a negative errno. * + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per + * PCIe r6.0, sec 5.5.4. + * * @pdev: PCI device * @state: Mask of ASPM link states to enable */ @@ -1432,6 +1435,9 @@ EXPORT_SYMBOL(pci_enable_link_state); * can't touch the LNKCTL register. Also note that this does not enable states * disabled by pci_disable_link_state(). Return 0 or a negative errno. * + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per + * PCIe r6.0, sec 5.5.4. + * * @pdev: PCI device * @state: Mask of ASPM link states to enable * -- 2.43.0
