Re: [Update PATCH 1/1] Cpufreq: Make governor data on nonboot cpusacross system suspend/resume

[Lan Tianyu]

On 11/15/2013 06:22 PM, Viresh Kumar wrote:
> On 15 November 2013 13:45, Lan Tianyu <tianyu.lan@xxxxxxxxx> wrote:
> > Currently, governor of nonboot cpus will be put to EXIT when system suspend.
> > Since all these cpus will be unplugged and the governor usage_count decreases
> > to zero. The governor data and its sysfs interfaces will be freed or released.
> > This makes user config of these governors loss during suspend and resume.
> >
> > This doesn't happen on the governor covering boot cpu because it isn't
> > unplugged during system suspend.
> >
> > To fix this issue, skipping governor exit during system suspend and check
> > policy governor data to determine whether the governor is really needed
> > to be initialized when do init. If not, return EALREADY to indicate the
> > governor has been initialized and should do nothing. __cpufreq_governor()
> > convert EALREADY to 0 as return value for INIT event since governor is
> > still under INIT state and can do START operation.
> >
> > Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> > ---
>
> Hi Lan..

Hi Viresh:

> Apologies!!
>
> I already had a solution for this as this was reported by few Broadcom people
> as well. But I haven't send it to mainline yet as it was untested. It
> looked similar
> to what you had..
>
> And so I would have taken your patch (as you have sent it first to the list and
> there is no real advantage of my patch over yours, they were almost same) :)
>
> But then I went chasing another bug posted by Nishant:
>
> https://lkml.org/lkml/2013/10/24/369
>
> And the final solution I have to write solved all the problems you and he
> reported.
>
> Please have a look at that patch (you are cc'd) and give it a try to see
> if it fixes your problem..

Never mind. I think it should work and will try it.

> Btw, One question about your setup:
> - you must have a multi cluster/socket SoC as you have atleast one more
> policy structure than used for group containing boot cpu..

Actually, I test on a laptop and find this issue when reading code to 
fix other bug. :)

All cpus have their own policys.

> - Are you using separate governor for both groups?

Just to produce the bug, I set one non-boot cpu to conservative gov. All 
other remain default "ondemand".

> - Or are you using CPUFREQ_HAVE_GOVERNOR_PER_POLICY stuff
> to use same governor with separate tunables for both groups?

No, I am not using this.

> Just wanted to know if somebody else is also using
> CPUFREQ_HAVE_GOVERNOR_PER_POLICY :)


--
Best Regards
Tianyu Lan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/