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The ->get callback in the intel_pstate structure was mostly there for the scaling_cur_freq sysfs attribute to work, but after commit f8475cef9008 (x86: use common aperfmperf_khz_on_cpu() to calculate KHz using APERF/MPERF) that attribute uses arch_freq_get_on_cpu() provided by the x86 arch code on all processors supported by intel_pstate, so it doesn't need the ->get callback from the driver any more. Moreover, the very presence of the ->get callback in the intel_pstate structure causes the cpuinfo_cur_freq attribute to be present when intel_pstate operates in the active mode, which is bogus, because the role of that attribute is to return the current CPU frequency as seen by the hardware. For intel_pstate, though, this is just an average frequency and not really current, but computed for the previous sampling interval (the actual current frequency may be way different at the point this value is obtained by reading from cpuinfo_cur_freq), and after commit 82b4e03e01bc (intel_pstate: skip scheduler hook when in "performance" mode) the value in cpuinfo_cur_freq may be stale or just 0, depending on the driver's operation mode. In fact, however, on the hardware supported by intel_pstate there is no way to read the current CPU frequency from it, so the cpuinfo_cur_freq attribute should not be present at all when this driver is in use. For this reason, drop intel_pstate_get() and clear the ->get callback pointer pointing to it, so that the cpuinfo_cur_freq is not present for intel_pstate in the active mode any more. Fixes: 82b4e03e01bc (intel_pstate: skip scheduler hook when in "performance" mode) Reported-by: Huaisheng Ye <yehs1@lenovo.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.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.