iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

cpufreq: CPPC: Use transition_delay_us depending transition_latency

Browse Source 
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>
This commit is contained in:
George Cherian 2018-03-23 03:30:31 -07:00 committed by Greg Kroah-Hartman
parent 9427a4aecf
commit f1e90bf95e
1 changed files with 3 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/cpufreq/cppc_cpufreq.c
View File

@ -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)