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>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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