Commit 904d9dcd authored by Zeng Heng's avatar Zeng Heng
Browse files

cpufreq: CPPC: keep target core awake when reading its cpufreq rate 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I73EPL



--------------------------------

As ARM AMU's document says, all counters are subject to any changes
in clock frequency, including clock stopping caused by the WFI and WFE
instructions.

Therefore, using smp_call_on_cpu() to trigger target CPU to
read self's AMU counters, which ensures the counters are working
properly during calculation.

Signed-off-by: default avatarZeng Heng <zengheng4@huawei.com>
parent 09f90a26

arch/arm64/kernel/cpufeature.c

+1 −0
Original line number Diff line number Diff line
@@ -1588,6 +1588,7 @@ bool cpu_has_amu_feat(int cpu) 
{

	return cpumask_test_cpu(cpu, &amu_cpus);

}

EXPORT_SYMBOL(cpu_has_amu_feat);



int get_cpu_with_amu_feat(void)

{

drivers/cpufreq/cppc_cpufreq.c

+20 −6
Original line number Diff line number Diff line
@@ -350,23 +350,37 @@ static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu, 
	return cppc_cpufreq_perf_to_khz(cpu, delivered_perf);

}



static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)

static int cppc_get_perf_ctrs_sample(void *val)

{

	struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};

	struct cppc_cpudata *cpu = all_cpu_data[cpunum];

	int cpunum = smp_processor_id();

	struct cppc_perf_fb_ctrs *fb_ctrs = val;

	int ret;



	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t0);

	ret = cppc_get_perf_ctrs(cpunum, fb_ctrs);

	if (ret)

		return ret;



	udelay(2); /* 2usec delay between sampling */



	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t1);

	return cppc_get_perf_ctrs(cpunum, fb_ctrs + 1);

}



static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)

{

	struct cppc_perf_fb_ctrs fb_ctrs[2] = {0};

	struct cppc_cpudata *cpu = all_cpu_data[cpunum];

	int ret;



	if (cpu_has_amu_feat(cpunum))

		ret = smp_call_on_cpu(cpunum, cppc_get_perf_ctrs_sample,

				      fb_ctrs, false);

	else

		ret = cppc_get_perf_ctrs_sample(fb_ctrs);



	if (ret)

		return ret;



	return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);

	return cppc_get_rate_from_fbctrs(cpu, fb_ctrs[0], fb_ctrs[1]);

}



static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)