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commit 95d6c0857e54b788982746071130d822a795026b upstream. Currently, intel_pstate doesn't register if _PSS is not present on HP Proliant systems, because it expects the firmware to take over CPU performance scaling in that case. However, if ACPI PCCH is present, the firmware expects the kernel to use it for CPU performance scaling and the pcc-cpufreq driver is loaded for that. Unfortunately, the firmware interface used by that driver is not scalable for fundamental reasons, so pcc-cpufreq is way suboptimal on systems with more than just a few CPUs. In fact, it is better to avoid using it at all. For this reason, modify intel_pstate to look for ACPI PCCH if _PSS is not present and register if it is there. Also prevent the pcc-cpufreq driver from trying to initialize itself if intel_pstate has been registered already. Fixes: fbbcdc0744da (intel_pstate: skip the driver if ACPI has power mgmt option) Reported-by: Andreas Herrmann <aherrmann@suse.com> Reviewed-by: Andreas Herrmann <aherrmann@suse.com> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Tested-by: Andreas Herrmann <aherrmann@suse.com> Cc: 4.16+ <stable@vger.kernel.org> # 4.16+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.