@@ -1539,6 +1539,44 @@ 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_ptm_state(struct pci_dev *dev)
+{
+ int ptm;
+ struct pci_cap_saved_state *save_state;
+ u16 *cap;
+
+ if (!pci_is_pcie(dev))
+ return;
+
+ ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
+ if (!ptm)
+ return;
+
+ save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
+ if (!save_state) {
+ pci_err(dev, "no suspend buffer for PTM\n");
+ return;
+ }
+
+ cap = (u16 *)&save_state->cap.data[0];
+ pci_read_config_word(dev, ptm + PCI_PTM_CTRL, cap);
+}
+
+static void pci_restore_ptm_state(struct pci_dev *dev)
+{
+ struct pci_cap_saved_state *save_state;
+ int ptm;
+ u16 *cap;
+
+ save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
+ ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
+ if (!save_state || !ptm)
+ return;
+
+ cap = (u16 *)&save_state->cap.data[0];
+ pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap);
+}
+
/**
* pci_save_state - save the PCI configuration space of a device before
* suspending
@@ -1566,6 +1604,7 @@ int pci_save_state(struct pci_dev *dev)
pci_save_ltr_state(dev);
pci_save_dpc_state(dev);
pci_save_aer_state(dev);
+ pci_save_ptm_state(dev);
return pci_save_vc_state(dev);
}
EXPORT_SYMBOL(pci_save_state);
@@ -1677,6 +1716,7 @@ void pci_restore_state(struct pci_dev *dev)
pci_restore_vc_state(dev);
pci_restore_rebar_state(dev);
pci_restore_dpc_state(dev);
+ pci_restore_ptm_state(dev);
pci_aer_clear_status(dev);
pci_restore_aer_state(dev);
@@ -3332,6 +3372,10 @@ 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_PTM, sizeof(u16));
+ if (error)
+ pci_err(dev, "unable to allocate suspend buffer for PTM\n");
+
pci_allocate_vc_save_buffers(dev);
}
The PCI subsystem does not currently save and restore the configuration space for the Precision Time Measurement (PTM) PCIe extended capability leading to the feature returning disabled on S3 resume. This has been observed on Intel Coffee Lake desktops. Add save/restore of the PTM control register. This saves the PTM Enable, Root Select, and Effective Granularity bits. Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: David E. Box <david.e.box@linux.intel.com> --- drivers/pci/pci.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+)