lkml.org 
[lkml]   [2017]   [Dec]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] cpufreq: longhaul: Set transition_delay_us to 20 ms
On Tue, Dec 5, 2017 at 9:54 AM, Meelis Roos <mroos@ut.ee> wrote:
>> > The commit e948bc8fbee0 ("cpufreq: Cap the default transition delay
>> > value to 10 ms") caused a regression on EPIA-M min-ITX computer where
>> > shutdown or reboot hangs occasionally with a print message like:
>> >
>> > longhaul: Warning: Timeout while waiting for idle PCI bus
>> > cpufreq: __target_index: Failed to change cpu frequency: -16
>> >
>> > This probably happens because the cpufreq governor tries to change the
>> > frequency of the CPU faster than allowed by the hardware.
>> >
>> > With the above commit, the default transition delay comes to 10 ms for a
>> > transition_latency of 200 us. Set the default transition delay to 20 ms
>> > directly to fix this regression.
>> >
>> > Fixes: e948bc8fbee0 ("cpufreq: Cap the default transition delay value to 10 ms")
>> > Cc: 4.14+ <stable@vger.kernel.org> # 4.14+
>> > Reported-by: Meelis Roos <mroos@linux.ee>
>> > Suggested-by: Rafael J. Wysocki <rjw@rjwysocki.net>
>> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
>> > ---
>> > drivers/cpufreq/longhaul.c | 2 +-
>> > 1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/cpufreq/longhaul.c b/drivers/cpufreq/longhaul.c
>> > index c46a12df40dd..56eafcb07859 100644
>> > --- a/drivers/cpufreq/longhaul.c
>> > +++ b/drivers/cpufreq/longhaul.c
>> > @@ -894,7 +894,7 @@ static int longhaul_cpu_init(struct cpufreq_policy *policy)
>> > if ((longhaul_version != TYPE_LONGHAUL_V1) && (scale_voltage != 0))
>> > longhaul_setup_voltagescaling();
>> >
>> > - policy->cpuinfo.transition_latency = 200000; /* nsec */
>> > + policy->transition_delay_us = 20000; /* usec */
>> >
>> > return cpufreq_table_validate_and_show(policy, longhaul_table);
>> > }
>>
>> This patch also works on my EPIA-M board - tested 10+ times.
>
> An on the last try just after sending the mail, it hung again in the
> same way as before - so maybe 20 is on the edge of being good.

OK, so can you please try to modify the patch to set
transition_delay_us to 30000, say, and see if that's reliable?

Thanks,
Rafael

\
 
 \ /
  Last update: 2017-12-05 16:26    [W:0.061 / U:0.488 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site