4.14-stable review patch. If anyone has any objections, please let me know.
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From: George Cherian george.cherian@cavium.com
commit 3d41386d556db9f720e00de3e11e45f39cb5071c upstream.
With commit e948bc8fbee0 (cpufreq: Cap the default transition delay value to 10 ms) the cpufreq was not honouring the delay passed via ACPI (PCCT). Due to which on ARM based platforms using CPPC the cpufreq governor tries to change the frequency of CPUs faster than expected.
This leads to continuous error messages like the following. " ACPI CPPC: PCC check channel failed. Status=0 "
Earlier (without above commit) the default transition delay was taken form the value passed from PCCT. Use the same value provided by PCCT to set the transition_delay_us.
Fixes: e948bc8fbee0 (cpufreq: Cap the default transition delay value to 10 ms) Signed-off-by: George Cherian george.cherian@cavium.com Cc: 4.14+ stable@vger.kernel.org # 4.14+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/cpufreq/cppc_cpufreq.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/cpufreq/cppc_cpufreq.c +++ b/drivers/cpufreq/cppc_cpufreq.c @@ -20,6 +20,7 @@ #include <linux/cpu.h> #include <linux/cpufreq.h> #include <linux/dmi.h> +#include <linux/time.h> #include <linux/vmalloc.h>
#include <asm/unaligned.h> @@ -162,6 +163,8 @@ static int cppc_cpufreq_cpu_init(struct policy->cpuinfo.max_freq = cppc_dmi_max_khz;
policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num); + policy->transition_delay_us = cppc_get_transition_latency(cpu_num) / + NSEC_PER_USEC; policy->shared_type = cpu->shared_type;
if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)