On Intel systems that support ACPI Low Power Idle it has been observed that the L1 Substate capability can return disabled after a s2idle cycle. This causes the loss of L1 Substate support during runtime leading to higher power consumption. Add save/restore of the L1SS control registers. Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx> --- drivers/pci/pci.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e578d34095e9..beee3d9952a6 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1539,6 +1539,48 @@ static void pci_restore_ltr_state(struct pci_dev *dev) pci_write_config_word(dev, ltr + PCI_LTR_MAX_NOSNOOP_LAT, *cap++); } +static void pci_save_l1ss_state(struct pci_dev *dev) +{ + int l1ss; + struct pci_cap_saved_state *save_state; + u16 *cap; + + if (!pci_is_pcie(dev)) + return; + + l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS); + if (!l1ss) + return; + + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS); + if (!save_state) { + pci_err(dev, "no suspend buffer for L1 Substates\n"); + return; + } + + cap = (u16 *)&save_state->cap.data[0]; + pci_read_config_word(dev, l1ss + PCI_L1SS_CTL1, cap++); + pci_read_config_word(dev, l1ss + PCI_L1SS_CTL1 + 2, cap++); + pci_read_config_word(dev, l1ss + PCI_L1SS_CTL2, cap++); +} + +static void pci_restore_l1ss_state(struct pci_dev *dev) +{ + struct pci_cap_saved_state *save_state; + int l1ss; + u16 *cap; + + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS); + l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS); + if (!save_state || !l1ss) + return; + + cap = (u16 *)&save_state->cap.data[0]; + pci_write_config_word(dev, l1ss + PCI_L1SS_CTL1, *cap++); + pci_write_config_word(dev, l1ss + PCI_L1SS_CTL1 + 2, *cap++); + pci_write_config_word(dev, l1ss + PCI_L1SS_CTL2, *cap++); +} + /** * pci_save_state - save the PCI configuration space of a device before * suspending @@ -1563,6 +1605,7 @@ int pci_save_state(struct pci_dev *dev) if (i != 0) return i; + pci_save_l1ss_state(dev); pci_save_ltr_state(dev); pci_save_dpc_state(dev); pci_save_aer_state(dev); @@ -1670,6 +1713,7 @@ void pci_restore_state(struct pci_dev *dev) */ pci_restore_ltr_state(dev); + pci_restore_l1ss_state(dev); pci_restore_pcie_state(dev); pci_restore_pasid_state(dev); pci_restore_pri_state(dev); @@ -3332,6 +3376,11 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev) if (error) pci_err(dev, "unable to allocate suspend buffer for LTR\n"); + error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_L1SS, + 3 * sizeof(u16)); + if (error) + pci_err(dev, "unable to allocate suspend buffer for L1 Substates\n"); + pci_allocate_vc_save_buffers(dev); } -- 2.20.1