Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Ben Gamari]

Viresh Kumar  writes:

> On 03-12-15, 11:26, Ben Gamari wrote:
>> Sounds reasonable to me. However, I'd just like to reiterate that this
>> line of work can be pursued independently from the upstreaming of this
>> series.
>
> I think this is the right time to upstream the right solution. Just
> try it once, if you face lots of difficulties or issues, then we can
> ofcourse see..
>
It looks like Bartlomiej has picked up this set. Regardless, while
tracking down various devicetree issues I noticed that the cpu-supply
and cpu%d-supply bindings appear to be completely undocumented. It
seem as though this ought to be fixed.

Cheers,

- Ben


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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Viresh Kumar]

On 03-12-15, 12:21, Ben Gamari wrote:
> Do you mean something along these lines? [1]

Yeah.

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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Viresh Kumar]

On 03-12-15, 11:05, Sudeep Holla wrote:
> The main difference is that we get the OPPs from the firmware rather
> than DT. We may just need to abstract that part and we should be able to
> use it. I will have a look at it and get back to you will more details.
> It has been a while since I looked at cpufreq-dt.

I forgot that :( .. but we can then create OPPs at runtime based on
what's available from firmware. And we also have an API now to set
which CPUs share OPPs... so that might be used as well..

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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Ben Gamari]

Viresh Kumar  writes:

> On 03-12-15, 11:26, Ben Gamari wrote:
>> Viresh Kumar  writes:
>> > But, before I start reviewing this series, I have few comments.
>> > - We weren't able to use cpufreq-dt driver for big LITTLE platforms
>> >   earlier, as it never had multi cluster support and we wanted
>> >   clock-sharing information via DT.
>> 
>> Fair enough.
>> 
>> > - That is all fixed now.
>> 
>> I did not see any mention of this in the cpufreq-dt driver binding
>> documentation, otherwise I would have tried going this route.
>> 
>> Do you have any references? I'd be happy to examine what would be
>> necessary to go this route although, being an independent contributor,
>> it may take time.
>
> You wouldn't find in cpufreq-dt documentation as its not specific to
> that. I have seen you DT patches now, and you have created the OPP
> tables mostly correctly. Just create the cpufreq-platform device for
> cpufreq-dt instead of arm-big-little one. And it should just work.
>
Do you mean something along these lines? [1]

>> Sounds reasonable to me. However, I'd just like to reiterate that this
>> line of work can be pursued independently from the upstreaming of this
>> series.
>
> I think this is the right time to upstream the right solution. Just
> try it once, if you face lots of difficulties or issues, then we can
> ofcourse see..
>
Sure. I didn't realize things were so close to being functional. Thanks
for the hint. I'll give it a shot next time my XU4 is free.

> NOTE: Check how OPP nodes are required to be created now in
> linux-next. They should be named like opp@. Something I
> noticed in your DTs.
>
I've fixed this in the branch.

Thanks again.

Cheers,

- Ben


[1] 
https://github.com/bgamari/linux/commit/285778aaff464d4dcf152f3e9e0df3d8c6909576


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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Sudeep Holla]

On 03/12/15 06:05, Viresh Kumar wrote:

[...]


@Sudeep: What would it take you to use cpufreq-dt for ARM's platforms
?



The main difference is that we get the OPPs from the firmware rather
than DT. We may just need to abstract that part and we should be able to
use it. I will have a look at it and get back to you will more details.
It has been a while since I looked at cpufreq-dt.

--
Regards,
Sudeep
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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Ben Gamari]

Viresh Kumar  writes:

> Hi Ben,

Hi Viresh,

> On 02-12-15, 22:19, Ben Gamari wrote:
>> 
>> This patch series adds cpufreq support for the Exynos 5800, 5420, and 5422
>> SOCs. In particular, it adds support for operating-points-v2 bindings to the
>> arm-big-little cpufreq driver and updates the above-mentioned SOCs' 
>> devicetrees
>> to take advantage of this support. There are also a couple of patches 
>> improving
>> the clarify of the arm-big-little implementation. It is built on a set posted
>> by Bartlomiej Zolnierkiewicz in April 2015.
>> 
>> The most signficant change from the original series is porting to the
>> operating-points-v2 devicetree bindings. The series has been tested by me on
>> and Odroid XU4 and by Javier Martinez Canillas on a Peach Pit.
>
> Thanks for working with opp-v2 bindings, really appreciate it.

My pleasure.

> But, before I start reviewing this series, I have few comments.
> - We weren't able to use cpufreq-dt driver for big LITTLE platforms
>   earlier, as it never had multi cluster support and we wanted
>   clock-sharing information via DT.

Fair enough.

> - That is all fixed now.

I did not see any mention of this in the cpufreq-dt driver binding
documentation, otherwise I would have tried going this route.

Do you have any references? I'd be happy to examine what would be
necessary to go this route although, being an independent contributor,
it may take time.

> - I want Samsung's big LITTLE platforms to use cpufreq-dt and drop
>   arm_big_little driver completely.

That sounds like a great direction going forward. However, I would still
kindly request that you consider this series.

The existence of future plans of course does not change the fact that
users have real hardware today; hardware that they have spent money on
and would like to use. Cpufreq support has already been deferred once
for similar reasons of interface churn which essentially forestalled
working functionality from entering the kernel by eight months; I'd
really like to avoid having this happen again.

> - The only case for which it (arm_big_little) driver might be useful
>   is the IKS solution. Which I don't believe you are going to use in
>   future :)

Indeed.

> My plan for the arm-big-little driver:
> - Migrate all platforms to use cpufreq-dt instead for non-IKS
>   solution
> - Make arm-big-little driver arm-big-little-iks only driver.

Sounds reasonable to me. However, I'd just like to reiterate that this
line of work can be pursued independently from the upstreaming of this
series.

Thanks for your time,

- Ben


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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Viresh Kumar]

On 03-12-15, 11:26, Ben Gamari wrote:
> Viresh Kumar  writes:
> > But, before I start reviewing this series, I have few comments.
> > - We weren't able to use cpufreq-dt driver for big LITTLE platforms
> >   earlier, as it never had multi cluster support and we wanted
> >   clock-sharing information via DT.
> 
> Fair enough.
> 
> > - That is all fixed now.
> 
> I did not see any mention of this in the cpufreq-dt driver binding
> documentation, otherwise I would have tried going this route.
> 
> Do you have any references? I'd be happy to examine what would be
> necessary to go this route although, being an independent contributor,
> it may take time.

You wouldn't find in cpufreq-dt documentation as its not specific to
that. I have seen you DT patches now, and you have created the OPP
tables mostly correctly. Just create the cpufreq-platform device for
cpufreq-dt instead of arm-big-little one. And it should just work.

> > - I want Samsung's big LITTLE platforms to use cpufreq-dt and drop
> >   arm_big_little driver completely.
> 
> That sounds like a great direction going forward. However, I would still
> kindly request that you consider this series.
> 
> The existence of future plans of course does not change the fact that
> users have real hardware today; hardware that they have spent money on
> and would like to use. Cpufreq support has already been deferred once
> for similar reasons of interface churn which essentially forestalled
> working functionality from entering the kernel by eight months; I'd
> really like to avoid having this happen again.

I am not talking about any future plans here that need some work to be
done. Its all working today, you just need to use a different driver.

> Sounds reasonable to me. However, I'd just like to reiterate that this
> line of work can be pursued independently from the upstreaming of this
> series.

I think this is the right time to upstream the right solution. Just
try it once, if you face lots of difficulties or issues, then we can
ofcourse see..

NOTE: Check how OPP nodes are required to be created now in
linux-next. They should be named like opp@. Something I
noticed in your DTs.

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[PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Ben Gamari]

This patch series adds cpufreq support for the Exynos 5800, 5420, and 5422
SOCs. In particular, it adds support for operating-points-v2 bindings to the
arm-big-little cpufreq driver and updates the above-mentioned SOCs' devicetrees
to take advantage of this support. There are also a couple of patches improving
the clarify of the arm-big-little implementation. It is built on a set posted
by Bartlomiej Zolnierkiewicz in April 2015.

The most signficant change from the original series is porting to the
operating-points-v2 devicetree bindings. The series has been tested by me on
and Odroid XU4 and by Javier Martinez Canillas on a Peach Pit.

Cheers,

- Ben

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Re: [PATCH v5 0/12] cpufreq: Add support for Exynos 5800, 5420, and 5422

[Viresh Kumar]

Hi Ben,

On 02-12-15, 22:19, Ben Gamari wrote:
> 
> This patch series adds cpufreq support for the Exynos 5800, 5420, and 5422
> SOCs. In particular, it adds support for operating-points-v2 bindings to the
> arm-big-little cpufreq driver and updates the above-mentioned SOCs' 
> devicetrees
> to take advantage of this support. There are also a couple of patches 
> improving
> the clarify of the arm-big-little implementation. It is built on a set posted
> by Bartlomiej Zolnierkiewicz in April 2015.
> 
> The most signficant change from the original series is porting to the
> operating-points-v2 devicetree bindings. The series has been tested by me on
> and Odroid XU4 and by Javier Martinez Canillas on a Peach Pit.

Thanks for working with opp-v2 bindings, really appreciate it.

But, before I start reviewing this series, I have few comments.
- We weren't able to use cpufreq-dt driver for big LITTLE platforms
  earlier, as it never had multi cluster support and we wanted
  clock-sharing information via DT.
- That is all fixed now.
- I want Samsung's big LITTLE platforms to use cpufreq-dt and drop
  arm_big_little driver completely.
- The only case for which it (arm_big_little) driver might be useful
  is the IKS solution. Which I don't believe you are going to use in
  future :)

My plan for the arm-big-little driver:
- Migrate all platforms to use cpufreq-dt instead for non-IKS
  solution
- Make arm-big-little driver arm-big-little-iks only driver.

@Sudeep: What would it take you to use cpufreq-dt for ARM's platforms
?

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viresh
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