Re: [PATCH v1 & v6 1/2] PM/devfreq: add suspend frequency support

[hl <hl@rock-chips.com>]

Hi Chanwoo Choi,

     I think the dev_pm_opp_get_suspend_opp() have implement most of
the funtion, all we need is just define the node in dts, like following:

&dmc_opp_table {
     opp06 {
         opp-suspend;
     };
};

so i think my way semm more simple.

On 2016年11月24日 15:10, Chanwoo Choi wrote:
> + Tobias Jakobi,
>
> Hi Lin,
>
> We need to discuss how to support the suspend-opp of devfreq device.
> Now, there are two patch thread for suspend-opp of devfreq.
>
> The Lin's approach modify the devfreq_suspend_device() to support suspend-opp.
> The Tobias's approach[1] add new devfreq_suspend() and then call it on dpm_suspend()
> when entering the suspend state.
>
> [1] [RFC 0/4] PM / devfreq: draft for OPP suspend impl
> - https://patchwork.kernel.org/patch/9443323/
> - https://patchwork.kernel.org/patch/9443325/
> - https://patchwork.kernel.org/patch/9443329/
> - https://patchwork.kernel.org/patch/9443331/
>
> I think we need to discuss it together.
>
> Regards,
> Chanwoo Choi
>
> On 2016년 11월 24일 15:45, hl wrote:
>> Hi MyungJoo Ham,
>>
>> On 2016年11月24日 14:14, MyungJoo Ham wrote:
>>> On Thu, Nov 24, 2016 at 11:18 AM, hl <hl@rock-chips.com> wrote:
>>>> Hi MyungJoo Ham,
>>> []
>>>>> We still need to sync the all status even i call target() in
>>>>> devfreq_suspend/resume_device
>>>>> directly, so still need update_devfreq() other setp except
>>>>> devfreq->governor->get_target_freq(devfreq, &freq);
>>>> And i think it better to be governor behaviors, for userspace they may not
>>>> want to change
>>>> the suspend frequency like other governor, the frequency should decide by
>>>> the user, if they
>>>> want this function, they should like other governor to rigister a
>>>> devfreq_monitor_suspend().
>>>> What do you think about my rev6 patch?
>>> If I understand the intention correctly, this is for the stability of
>>> the device due to the behavior or bootloader/SoC-initializer, which
>>> has nothing to do with governors.
>>>
>>> Even if users are using userspace, as long as they set the custom
>>> frequencies lower than the default, they have the possibility of
>>> being unstable as ondemand is going to have.
>>>
>>>
>>> To reuse the update_devfreq() code, you may do something like:
>>>
>>> static int _update_freq(struct devfreq *devfreq, bool is_suspending)
>>> {
>>>      /* original contents of update_freq with if statement with is_suspending wrapping get_target_freq */
>>> }
>>> int update_freq(struct devfreq *devfreq)
>>> {
>>> 	return _update_freq(devfreq, false);
>>> }
>>>
>>>
>>> There should be other good non-invasive methods that are not governoe-specific as well.
>>>
>> Thanks for your suggestion, i will update the new version soon.
>>> Cheers,
>>> MyungJoo
>>>
>>>
>>>
>>>
>>> _______________________________________________
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>>> Linux-rockchip@lists.infradead.org
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>> -- 
>> Lin Huang
>>
>
>
>

-- 
Lin Huang