Re: [PATCH 6/8] OMAP: PM CONSTRAINTS: implement the devices wake-up latency constraints

[Kevin Hilman <khilman@ti.com>]

Jean Pihet <jean.pihet@newoldbits.com> writes:

> Kevin,
>
> On Fri, Sep 16, 2011 at 1:47 AM, Kevin Hilman <khilman@ti.com> wrote:
>> Jean Pihet <jean.pihet@newoldbits.com> writes:
>>
>>> Implement the devices wake-up latency constraints using the global
>>> device PM QoS notification handler which applies the constraints to the
>>> underlying layer by calling the corresponding function at hwmod level.
>>>
>>> Note: the bus throughput function is implemented but currently is
>>> a no-op. A new PM QoS class for the bus throughput needs to be
>>> added.
>>>
>>> Tested on OMAP3 Beagleboard and OMAP4 Pandaboard in RET/OFF using wake-up
>>> latency constraints on MPU, CORE and PER.
>>>
>>> Signed-off-by: Jean Pihet <j-pihet@ti.com>
>>
>> This patch does 2 things.
>>
>> 1) removes the MPU lat stuff from the OMAP PM layer (since it's now
>>   available in a generic form
>> 2) implements device wake-up latency constraints
>>
>> This should be broken up into two parts.
>>
>> Also, this patch seems to remove a bunch of stuff that was just added in
>> patch 2/8.  Probably best to create the new OMAP PM layer after remving
>> the unused stuff.
>>
>> It think the code using the new per-device PM QoS API should also live
>> outside the OMAP PM layer, since it's not related, and we want to get
>> rid of the OMAP PM layer eventually.
>>
>> Speaking of which..., the more I think about it, the more I think we
>> should take this opportunity to clean and/or remove the OMAP PM layer
>> completely.
>
>
> I agree completely, the OMAP PM 'plugin' layer is useless and anyway
> an empty implementation for now.

Great, let's wait for Paul's view on this since he's the maintainer of
the OMAP PM layer.

>> With your work, other than the no-op bus throughput API, it's basically
>> unused.  I think that rather than creating a new OMAP PM layer just to
>> have a a no-op bus throughput function here, I think it's time
>> to remove OMAP PM completely.
>
> Ok. The only useful code is to register a PM QoS notifier in order to
> apply the constraints to the power domains.
> Are you suggesting to move this code to e.g. pmxxx.c?

Yes, or simply pm-constraints.c since I guess it should be
SoC-independent.

Kevin
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