Re: Nokia N900: Proper C-states

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 02/09/2016 04:56 PM, Tony Lindgren wrote:
> * Daniel Lezcano <daniel.lezcano@linaro.org> [160102 14:01]:
>> On 01/02/2016 03:26 PM, Pali Rohár wrote:
>>> Hello,
>>>
>>> due to this Daniel Lezcano commit (ARM: OMAP3: cpuidle - remove rx51
>>> cpuidle parameters table)
>>>
>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=231900afba52d6faddfb480cde4132d4edc089bc
>>>
>>> we need patch cpuidle34xx.c code to fix commit for Nokia N900. See:
>>>
>>> https://github.com/pali/linux-n900/commit/e147fd4b678f1f3d7a5235287910960bd41e04dc
>>>
>>> As Nokia N900 code is converting from legacy board code to DST, I would
>>> like to know how to patch correctly omap3_idle_driver in DTS with
>>> correct values measured for Nokia N900. Thanks!
>
> I'm almost certain those values are not n900 specific but should be
> used for omap3430 in general.
>
>> the conversion to the DT based arm cpuidle driver could be a bit complex
>> with one issue (index 0 != cpu_do_idle()) and one performance regression
>> (cpu_pm_enter/exit will be called in retention mode, even if this is not
>> needed).
>>
>> It will result in a PM code only on one side and on the other side, the
>> generic cpuidle-arm.c driver will be used instead with the DT definition. It
>> is worth to the conversion because the result will be nice IMO.
>>
>> Added Lorenzo who is initially author of the arm generic driver. We already
>> discussed in the past about those two issues above and I think this is
>> something we should improve.
>
> While this conversion process is going on, we could just add
> omap3430_idle_driver and set that based on cpu_is_omap3430()
> in omap3_idle_init().

Yes, that could be a temporary alternative.




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