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

From: hl
Date: Thu Nov 24 2016 - 02:34:56 EST

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 {

so i think my way semm more simple.

On 2016å11æ24æ 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

I think we need to discuss it together.

Chanwoo Choi

On 2016ë 11ì 24ì 15:45, hl wrote:
Hi MyungJoo Ham,

On 2016å11æ24æ 14:14, MyungJoo Ham wrote:
On Thu, Nov 24, 2016 at 11:18 AM, hl <hl@xxxxxxxxxxxxxx> wrote:
Hi MyungJoo Ham,
We still need to sync the all status even i call target() in
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
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.

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Lin Huang

Lin Huang