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Commit 54c6fd56 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'pm-4.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 

Pull power management fix from Rafael Wysocki:
 "This fixes a regression from the 4.14 cycle in the CPPC cpufreq driver
  causing it to use an incorrect transition delay value which leads to a
  very high rate of frequency change requests when the schedutil
  governor is in use (Prashanth Prakash)"

* tag 'pm-4.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq / CPPC: Set platform specific transition_delay_us
parents c33ede14 d4f3388a

drivers/cpufreq/cppc_cpufreq.c

+44 −2
Original line number Diff line number Diff line
@@ -126,6 +126,49 @@ static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy) 
				cpu->perf_caps.lowest_perf, cpu_num, ret);

}



/*

 * The PCC subspace describes the rate at which platform can accept commands

 * on the shared PCC channel (including READs which do not count towards freq

 * trasition requests), so ideally we need to use the PCC values as a fallback

 * if we don't have a platform specific transition_delay_us

 */

#ifdef CONFIG_ARM64

#include <asm/cputype.h>



static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)

{

	unsigned long implementor = read_cpuid_implementor();

	unsigned long part_num = read_cpuid_part_number();

	unsigned int delay_us = 0;



	switch (implementor) {

	case ARM_CPU_IMP_QCOM:

		switch (part_num) {

		case QCOM_CPU_PART_FALKOR_V1:

		case QCOM_CPU_PART_FALKOR:

			delay_us = 10000;

			break;

		default:

			delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;

			break;

		}

		break;

	default:

		delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;

		break;

	}



	return delay_us;

}



#else



static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)

{

	return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;

}

#endif



static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)

{

	struct cppc_cpudata *cpu;
@@ -162,8 +205,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy) 
		cpu->perf_caps.highest_perf;

	policy->cpuinfo.max_freq = cppc_dmi_max_khz;



	policy->transition_delay_us = cppc_get_transition_latency(cpu_num) /

		NSEC_PER_USEC;

	policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);

	policy->shared_type = cpu->shared_type;



	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {