[Query]set clk rate must operate its coordinated clock

[Query]set clk rate must operate its coordinated clock

[Jisheng Zhang]

Dear Stephen, Michael, Sebastian and all, 

I have the following clk case which I dunno the elegant solution:


cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
have to set its parent's freq, I.E cpupll freq. But before changing the
cpupll's freq, we should set its refclk as its parent firstly.

AFAIK, this is a common case, I have seen such requirement in rockchip, samsung
clk driver. They solve this by notifier, but as pointed out by Michael
in http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.html

"This is also a hack and it points towards some missing infrastructure in the
clock framework."

I also don't like the notifier solution, I believe the elegant solution could
be using the coordinated clock infrastructure. So what's the status of
this infrastructure? I can test, and I can even add some code to make it be
ready to be merged if you guide me ;)

Thanks in advance,
Jisheng

[Query]set clk rate must operate its coordinated clock

[Jisheng Zhang]

make it more clear below.

On Wed, 9 Mar 2016 15:24:20 +0800 Jisheng Zhang wrote:

> Dear Stephen, Michael, Sebastian and all, 
> 
> I have the following clk case which I dunno the elegant solution:
> 
> 
> cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
> have to set its parent's freq, I.E cpupll freq. But before changing the
> cpupll's freq, we should set its refclk as its parent firstly.

before changing cpupll's freq, we should set the refclk as cpuclk's parent firstly.

> 
> AFAIK, this is a common case, I have seen such requirement in rockchip, samsung
> clk driver. They solve this by notifier, but as pointed out by Michael
> in http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.html
> 
> "This is also a hack and it points towards some missing infrastructure in the
> clock framework."
> 
> I also don't like the notifier solution, I believe the elegant solution could
> be using the coordinated clock infrastructure. So what's the status of
> this infrastructure? I can test, and I can even add some code to make it be
> ready to be merged if you guide me ;)
> 
> Thanks in advance,
> Jisheng
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[Query]set clk rate must operate its coordinated clock

[Michael Turquette]

Jisheng,

Quoting Jisheng Zhang (2016-03-08 23:24:20)
> Dear Stephen, Michael, Sebastian and all, 
> 
> I have the following clk case which I dunno the elegant solution:
> 
> 
> cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
> have to set its parent's freq, I.E cpupll freq. But before changing the
> cpupll's freq, we should set its refclk as its parent firstly.
> 
> AFAIK, this is a common case, I have seen such requirement in rockchip, samsung
> clk driver. They solve this by notifier, but as pointed out by Michael
> in http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.html
> 
> "This is also a hack and it points towards some missing infrastructure in the
> clock framework."
> 
> I also don't like the notifier solution, I believe the elegant solution could
> be using the coordinated clock infrastructure. So what's the status of
> this infrastructure? I can test, and I can even add some code to make it be
> ready to be merged if you guide me ;)

Thanks for the email. I hope to finish that feature before ELC. I have
Cc'd Pi-Cheng Chen from Mediatek who is also interested in coordinated
clock rates.

Regards,
Mike

> 
> Thanks in advance,
> Jisheng

[Query]set clk rate must operate its coordinated clock

[Jisheng Zhang]

Dear Mike,

On Fri, 11 Mar 2016 08:51:52 -0800 Michael Turquette wrote:

> Jisheng,
> 
> Quoting Jisheng Zhang (2016-03-08 23:24:20)
> > Dear Stephen, Michael, Sebastian and all, 
> > 
> > I have the following clk case which I dunno the elegant solution:
> > 
> > 
> > cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
> > have to set its parent's freq, I.E cpupll freq. But before changing the
> > cpupll's freq, we should set its refclk as its parent firstly.
> > 
> > AFAIK, this is a common case, I have seen such requirement in rockchip, samsung
> > clk driver. They solve this by notifier, but as pointed out by Michael
> > in http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.html
> > 
> > "This is also a hack and it points towards some missing infrastructure in the
> > clock framework."
> > 
> > I also don't like the notifier solution, I believe the elegant solution could
> > be using the coordinated clock infrastructure. So what's the status of
> > this infrastructure? I can test, and I can even add some code to make it be
> > ready to be merged if you guide me ;)  
> 
> Thanks for the email. I hope to finish that feature before ELC. I have
> Cc'd Pi-Cheng Chen from Mediatek who is also interested in coordinated
> clock rates.
> 

Glad to hear that. I will test the infrastructure once it's sent out.

Thanks,
Jisheng

[Query]set clk rate must operate its coordinated clock

[Pi-Cheng Chen]

+linux-mediatek list

On Sat, Mar 12, 2016 at 12:51 AM, Michael Turquette
<mturquette@baylibre.com> wrote:
> Jisheng,
>
> Quoting Jisheng Zhang (2016-03-08 23:24:20)
>> Dear Stephen, Michael, Sebastian and all,
>>
>> I have the following clk case which I dunno the elegant solution:
>>
>>
>> cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
>> have to set its parent's freq, I.E cpupll freq. But before changing the
>> cpupll's freq, we should set its refclk as its parent firstly.
>>
>> AFAIK, this is a common case, I have seen such requirement in rockchip, samsung
>> clk driver. They solve this by notifier, but as pointed out by Michael
>> in http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.html
>>
>> "This is also a hack and it points towards some missing infrastructure in the
>> clock framework."
>>
>> I also don't like the notifier solution, I believe the elegant solution could
>> be using the coordinated clock infrastructure. So what's the status of
>> this infrastructure? I can test, and I can even add some code to make it be
>> ready to be merged if you guide me ;)
>
> Thanks for the email. I hope to finish that feature before ELC. I have
> Cc'd Pi-Cheng Chen from Mediatek who is also interested in coordinated
> clock rates.

Hi Mike,

Sorry for my late response.
Glad to hear that you're still working on it.
I am ready to test it on Mediatek platform.
Looking forwards to the new clk feature.

Thanks,
Pi-Cheng

>
> Regards,
> Mike
>
>>
>> Thanks in advance,
>> Jisheng

[Query]set clk rate must operate its coordinated clock

[Heiko Stübner]

Hi Mike,

Am Freitag, 11. M?rz 2016, 08:51:52 schrieb Michael Turquette:
> Quoting Jisheng Zhang (2016-03-08 23:24:20)
> > I have the following clk case which I dunno the elegant solution:
> > 
> > 
> > cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
> > have to set its parent's freq, I.E cpupll freq. But before changing the
> > cpupll's freq, we should set its refclk as its parent firstly.
> > 
> > AFAIK, this is a common case, I have seen such requirement in rockchip,
> > samsung clk driver. They solve this by notifier, but as pointed out by
> > Michael in
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.ht
> > ml
> > 
> > "This is also a hack and it points towards some missing infrastructure in
> > the clock framework."
> > 
> > I also don't like the notifier solution, I believe the elegant solution
> > could be using the coordinated clock infrastructure. So what's the status
> > of this infrastructure? I can test, and I can even add some code to make
> > it be ready to be merged if you guide me ;)
> 
> Thanks for the email. I hope to finish that feature before ELC. I have
> Cc'd Pi-Cheng Chen from Mediatek who is also interested in coordinated
> clock rates.

pulling this up again, did this materialize yet? :-)

Because it looks like on Rockchip we're getting yet another clock that needs 
special handling (set_rate needs to go through the trusted-firmware, while 
reading stays the same) which might profit from that as well.


Heiko

[Query]set clk rate must operate its coordinated clock

[Georgi Djakov]

On 06/06/2016 11:10 AM, Heiko St?bner wrote:
> Hi Mike,
> 
> Am Freitag, 11. M?rz 2016, 08:51:52 schrieb Michael Turquette:
>> Quoting Jisheng Zhang (2016-03-08 23:24:20)
>>> I have the following clk case which I dunno the elegant solution:
>>>
>>>
>>> cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
>>> have to set its parent's freq, I.E cpupll freq. But before changing the
>>> cpupll's freq, we should set its refclk as its parent firstly.
>>>
>>> AFAIK, this is a common case, I have seen such requirement in rockchip,
>>> samsung clk driver. They solve this by notifier, but as pointed out by
>>> Michael in
>>> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.ht
>>> ml
>>>
>>> "This is also a hack and it points towards some missing infrastructure in
>>> the clock framework."
>>>
>>> I also don't like the notifier solution, I believe the elegant solution
>>> could be using the coordinated clock infrastructure. So what's the status
>>> of this infrastructure? I can test, and I can even add some code to make
>>> it be ready to be merged if you guide me ;)
>>
>> Thanks for the email. I hope to finish that feature before ELC. I have
>> Cc'd Pi-Cheng Chen from Mediatek who is also interested in coordinated
>> clock rates.
> 
> pulling this up again, did this materialize yet? :-)
> 
> Because it looks like on Rockchip we're getting yet another clock that needs 
> special handling (set_rate needs to go through the trusted-firmware, while 
> reading stays the same) which might profit from that as well.
> 

Hi,
I am also interested in the CCR. Hopefully Mike will post some patches on
the list soon.

Regards,
Georgi