lkml.org 
[lkml]   [2020]   [Oct]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [Patch 2/2] cpufreq: tegra194: Fix unlisted boot freq warning
From
Date
>>
>>>> Warning coming during boot because the boot freq set by bootloader
>>>> gets filtered out due to big freq steps while creating freq_table.
>>>> Fixing this by setting closest ndiv value from freq_table.
>>>> Warning:
>>>> cpufreq: cpufreq_online: CPU0: Running at unlisted freq
>>>> cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed
>>>>
>>>> Also, added change in init to wait till current frequency becomes
>>>> equal or near to the previously requested frequency. This is done
>>>> because it takes some time to restore the previous frequency while
>>>> turning-on non-boot cores during exit from SC7(Suspend-to-RAM).
>>>
>>> So you are trying to figure if the frequency is listed in freq-table or not,
>>> otherwise setting the frequency to a value you think is appropriate. Right ?
>> During boot, want to set the frequency from freq_table which is closest to
>> the one set by bootloader.
>
> Right.
>
>> During resume from suspend-to-idle, want to restore the frequency which was
>> set on non-boot cores before they were hotplug powered off.
>
> Why exactly do you want to do that ? Rather you should provide
> online/offline hooks for the cpufreq driver and do light-weight
> suspend/resume as is done by cpufreq-dt.c as well.
>
Thank you for pointer. Added online hook to avoid warning during
hot-plug-on for the non-boot CPU's while exiting from Suspend-to-RAM. Will
send new version with the changes.

>>>
>>> This is what the cpufreq core already does when it printed these boot time
>>> messages. Do we really need to add this much code in here ?
>> We want to avoid the warning messages.
>
> Hmm, okay.
>
>>>
>>> If you really don't want to see the warning, how about fixing it the way cpufreq
>>> core does ? i.e. with this call:
>>>
>>> ret = __cpufreq_driver_target(policy, policy->cur - 1, CPUFREQ_RELATION_L);
>>>
>> The cpufreq core change will help in bootup case but not during the case of
>> resume.
>> In this change, reading the previously stored value and restoring it will
>> also fix the warning message during resume.
>
> You were getting the message during resume as well ? Why ? The
> firmware is updating the frequency to a previous value ? If that is
> so, you should just set the frequency again to some other value during
> resume to fix it.
Yes, it boots at a predefined frequency and then some time is taken to
restore the last frequency which software requested before entering
Suspend-to-RAM. We don't need to re-write the register again.

>
> --
> viresh
>

\
 
 \ /
  Last update: 2020-10-08 13:12    [W:0.046 / U:0.488 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site