lkml.org 
[lkml]   [2018]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.16 002/196] cpufreq: CPPC: Use transition_delay_us depending transition_latency
    Date
    4.16-stable review patch.  If anyone has any objections, please let me know.

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

    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)

    \
     
     \ /
      Last update: 2018-04-22 18:17    [W:4.952 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site