f5c8cf2a49
Commit 46573fd6369f ("cpufreq: intel_pstate: hybrid: Rework HWP
calibration") attempted to use the information from CPPC (the nominal
performance in particular) to obtain the scaling factor allowing the
frequency to be computed if the HWP performance level of the given CPU
is known or vice versa.
However, it turns out that on some platforms this doesn't work, because
the CPPC information on them does not align with the contents of the
MSR_HWP_CAPABILITIES registers.
This basically means that the only way to make intel_pstate work on all
of the hybrid platforms to date is to use the observation that on all
of them the scaling factor between the HWP performance levels and
frequency for P-cores is 78741 (approximately 100000/1.27). For
E-cores it is 100000, which is the same as for all of the non-hybrid
"core" platforms and does not require any changes.
Accordingly, make intel_pstate use 78741 as the scaling factor between
HWP performance levels and frequency for P-cores on all hybrid platforms
and drop the dependency of the HWP calibration code on CPPC.
Fixes: 46573fd6369f ("cpufreq: intel_pstate: hybrid: Rework HWP calibration")
Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 5.15+ <stable@vger.kernel.org> # 5.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.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.