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Rafael J. Wysocki
46573fd636
The current HWP calibration for hybrid processors in intel_pstate is fragile, because it depends too much on the information provided by the platform firmware via CPPC which may not be reliable enough. It also need not be so complicated. In order to improve that mechanism and make it more resistant to platform firmware issues, make it only use the CPPC nominal_perf values to compute the HWP-to-frequency scaling factors for all CPUs and possibly use the HWP_CAP highest_perf values to recompute them if the ones derived from the CPPC nominal_perf values alone appear to be too high. Namely, fetch CPC.nominal_perf for all CPUs present in the system, find the minimum one and use it as a reference for computing all of the CPUs' scaling factors (using the observation that for the CPUs having the minimum CPC.nominal_perf the HWP range of available performance levels should be the same as the range of available "legacy" P-states and so the HWP-to-frequency scaling factor for them should be the same as the corresponding scaling factor used for representing the P-state values in kHz). Signed-off-by: Rafael J. Wysocki <[email protected]> Tested-by: Zhang Rui <[email protected]>
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.