Re: [Patch 2/2] cpufreq: tegra194: Fix unlisted boot freq warning

[Sumit Gupta]

> > > > 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