Re: [GIT PULL] clk: ti: clock driver code migration to drivers

[Tero Kristo <t-kristo@ti.com>]

On 07/16/2015 04:51 AM, Paul Walmsley wrote:
> On Tue, 14 Jul 2015, Tony Lindgren wrote:
>
>> * Tero Kristo <t-kristo@ti.com> [150714 03:34]:
>>> On 07/14/2015 12:54 PM, Tony Lindgren wrote:
>>>> * Tero Kristo <t-kristo@ti.com> [150714 01:56]:
>>>>>
>>>>> This pull request contains the TI clock driver set to move the clock
>>>>> implementations under clock driver. Some small portions of the clock driver
>>>>> code still remain under mach-omap2 after this, it should be decided whether
>>>>> this code is now obsolete and should be deleted or should someone try to fix
>>>>> it.
>>>>
>>>> Hmm care to clarify what is obsolete or broken after this series?
>>>
>>> Not after this series, was broken/obsolete already before.
>>>
>>> A couple of omap2/omap3 specific clock files still remain under mach-omap2,
>>> they are DVFS related. OMAP3 core dvfs support is currently completely
>>> unused (this could probably be removed, or shall we re-introduce the painful
>>> core dvfs at some point again?), and parts of the omap2 core dpll handling
>>> code should probably be re-written; or at least verified that it actually
>>> works properly. I can't test OMAP2 DVFS myself so don't dare to fiddle with
>>> it.... I could probably try to get some sort of DVFS test case to work on
>>> the board farm OMAP2 board I have access to though, I can investigate this.
>>
>> People seem to still want the 1 GiHz support, but I think that only
>> depends on the SmartReflex and some kind of replacement for
>> voltagedomains. So if the core DVFS support is unused, I doubt it's
>> very high on anybody's list right now.
>
> At least several years ago, basic CORE DVFS support was working on OMAP3.
> The clock source changed rate, DRAM parameters were
> changed on the SDRC, etc.  What was not implemented was pre-rate-change
> and post-rate-change notifiers in many of the device drivers, because the
> infrastructure didn't exist at the time in the clock code.

Yes this is true, Nokia did an internal implementation for the pre/post 
notifier stuff which was never accepted upstream. The core dvfs code is 
no longer used in kernel for anything, it is just built in. The 
usefulness of the whole feature can be debated also, the use cases where 
it actually gives power savings is rather limited.

I'll post a patch to remove the 'dead' core-dvfs code to the list, we 
can debate the issue there.

-Tero