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SubjectRe: [PATCH] cpufreq: cppc: Use transition_delay_us depending on the transition_latency
Date
On Friday, March 23, 2018 11:30:31 AM CEST George Cherian wrote:
> 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 CPU faster than expeted.
>
> 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>
> ---
> drivers/cpufreq/cppc_cpufreq.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index a1c3025..dcb1cb9 100644
> --- 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 cpufreq_policy *policy)
> 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)
>

Applied, thanks!


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