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PCI/PTM: Save/restore Precision Time Measurement Capability for suspend/resume

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The PCI subsystem does not currently save and restore the configuration
space for the Precision Time Measurement (PTM) Extended Capability leading
to the possibility of 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>
Link: https://lore.kernel.org/r/20201207223951.19667-1-david.e.box@linux.intel.com
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
David E. Box
2020-12-07 14:39:50 -08:00
committed by Bjorn Helgaas
parent f8394f232b
commit 39850ed510
3 changed files with 53 additions and 0 deletions
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2
drivers/pci/pci.c
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@@ -1566,6 +1566,7 @@ 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 +1678,7 @@ 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);