Re: [PATCH 7/8] ir-rx51: Remove MPU wakeup latency adjustments

[Timo Kokkonen <timo.t.kokkonen@iki.fi>]

On 08/24/12 12:04, Jean Pihet wrote:
> Hi Timo,
> 
> On Fri, Aug 24, 2012 at 10:14 AM, Timo Kokkonen <timo.t.kokkonen@iki.fi> wrote:
>> Hi Jean,
>>
>> On 08/23/12 14:58, Jean Pihet wrote:
>>> Hi Timo,
>>>
>>> On Wed, Aug 22, 2012 at 9:50 PM, Timo Kokkonen <timo.t.kokkonen@iki.fi> wrote:
>>> That is correct. The API to use is the PM QoS API which cpuidle uses
>>> to determine the next MPU state based on the allowed latency.
>>>
>>>> A more appropriate fix for the problem would be to modify the idle
>>>> layer so that it does not allow MPU going to too deep sleep modes when
>>>> it is expected that the timers need to wake up MPU.
>>> The idle layer already uses the PM QoS framework to decide the next
>>> MPU state. I think the right solution is to convert from
>>> omap_pm_set_max_mpu_wakeup_lat to the PM QoS API.
>>>
>>> Cf. http://marc.info/?l=linux-omap&m=133968658305580&w=2 for an
>>> example of the conversion.
>>>
>>
>> Thanks. It looks like really easy and straightforward conversion.
>> However, I couldn't find the patch you were referring to from any trees
> Correct, this patch is not applied to the mainline code yet, it is
> provided as an example of the conversion.
> 
>> I could find. So, I take that this API does not really have omap2
>> support in it yet? I tried git grepping through the source and to me it
>> appears there is nothing in place yet that actually restricts the MPU
>> sleep states on omap2 when requested.
> The MPU state is controlled from the cpuidle framework, which
> retrieves the MPU allowed latency from the PM QoS framework. This is
> supported on OMAP2.
> Cf. the table of states and the associated latency in
> arch/arm/mach-omap2/cpuidle34xx.c.
> 

Thanks for the pointer. I took a look at the state table and adjusted
the latency requirements in my code. If I lower the latency from 50us to
10us, the timers are then waking up as they should be.

I'll replace this patch with one where I convert it using the new API.

Thanks!

-Timo