Re: [PATCH 1/1] OMAP3: PM: Fix compilation issue of omap3_pm_init_opp_table

[Nishanth Menon <nm@ti.com>]

Dasgupta, Romit had written, on 01/19/2010 08:50 AM, the following:
> Menon, Nishanth wrote:
>> Dasgupta, Romit had written, on 01/19/2010 08:43 AM, the following:
>>>>> 3430 opps, and we should move it to opp34xx.c(I hate having new files :( )..
>>>>> It should be only
>>>>> #ifdef CONFIG_CPU_FREQ. OPP has nothing to do with CONFIG_PM.
>>>>>
>>>>> Why do you need CPU_FREQ for suspend/resume??
>>>>>
>>>> voltage control - SR needs to query for voltage?
>>>>
>>> Why should suspend/resume be dependent on SR?
>> please see the code logic -> when SR is enabled and OFF/RET happens, you 
>> need the voltage for the current frequency so that you can disable SR, 
>> set the nominal voltage for the current OPP then go to WFI.
>>
> You do not need the OPP table for querying voltage alone. You can read that from
> the OMAP chip registers directly. So OPP layer is not necessary when we do not
> use cpufreq!
there are multiple ways to use SR -> Not all of them can use OMAP chip 
registers. certain class of devices would need to use PMICs, further SRF 
or it's equivalent will need to query the table for knowing what voltage 
corresponds to frequency, DSPBRidge needs to report to the baseimage 
what voltage corresponds to the frequency for the baseimage's load 
balancing/power decision logic etc.. in short when dynamic voltage 
scaling is needed, we need OPP layer a.k.a CONFIG_PM needs opp layer - 
not just cpufreq.

-- 
Regards,
Nishanth Menon