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>

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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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8

drivers/pci/pci.h

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43

drivers/pci/pcie/ptm.c

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