CPPC (Collaborative Processor Performance Control) offers optional registers which can be used to tune the system based on energy and/or performance requirements. Newer AMD processors add support for a subset of these optional CPPC registers, based on ACPI v6.1. The following are the supported CPPC registers for which sysfs entries are created: * enable (NEW) * max_perf (NEW) * min_perf (NEW) * energy_perf * lowest_perf * nominal_perf * desired_perf (NEW) * feedback_ctrs * auto_sel_enable (NEW) * lowest_nonlinear_perf The CPPC driver is updated to enable the OSPM and the userspace to access the newly supported registers. The purpose of exposing the registers via the sysfs entries is to allow the userspace to: * Tweak the values to fit its workload. * Apply a profile from AMD's optimization guides. Profiles will be documented in the performance/optimization guides. Note: * AMD systems will not have a policy applied in the kernel at this time. * By default, acpi_cpufreq will still be used. TODO: * Create a linux userspace tool that will help users generate a CPPC profile for their target workload. * Create or update a driver to apply a general CPPC policy in the kernel. Janakarajan Natarajan (1): acpi/cppc: Ensure only supported CPPC sysfs entries are created Yazen Ghannam (5): acpi/cppc: Modify show_cppc_data macro acpi/cppc: Rework cppc_set_perf() to use cppc_regs index acpi/cppc: Add macros to define a R/W sysfs entry for CPPC registers acpi/cppc: Add support for optional CPPC registers acpi/cppc: Add support for CPPC Enable register drivers/acpi/cppc_acpi.c | 363 +++++++++++++++++++++++++++++---- drivers/cpufreq/cppc_cpufreq.c | 6 +- include/acpi/cppc_acpi.h | 6 +- 3 files changed, 333 insertions(+), 42 deletions(-) -- 2.17.1
