Re: [PATCH v5 04/12] PM / devfreq: Add struct devfreq_policy

[Matthias Kaehlcke <mka@chromium.org>]

Hi,

On Wed, Jul 04, 2018 at 11:51:30AM +0900, Chanwoo Choi wrote:
> Hi,
> 
> On 2018년 07월 04일 08:46, Matthias Kaehlcke wrote:
> > Move variables related with devfreq policy changes from struct devfreq
> > to the new struct devfreq_policy and add a policy field to struct devfreq.
> > 
> > The following variables are moved:
> > 
> > df->min/max_freq           =>   p->user.min/max_freq
> > df->scaling_min/max_freq   =>   p->devinfo.min/max_freq
> > df->governor               =>   p->governor
> > df->governor_name          =>   p->governor_name
> > 
> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > Reviewed-by: Brian Norris <briannorris@chromium.org>
> > ---
> > Changes in v5:
> > - none
> > 
> > Changes in v4:
> > - added 'Reviewed-by: Brian Norris <briannorris@chromium.org>' tag
> > 
> > Changes in v3:
> > - none
> > 
> > Changes in v2:
> > - performance, powersave and simpleondemand governors don't need changes
> >   with "PM / devfreq: Don't adjust to user limits in governors"
> > - formatting fixes
> > ---
> >  drivers/devfreq/devfreq.c          | 137 ++++++++++++++++-------------
> >  drivers/devfreq/governor_passive.c |   4 +-
> >  include/linux/devfreq.h            |  38 +++++---


> >  3 files changed, 103 insertions(+), 76 deletions(-)
> > 
> 
> (skip)
> 
> >  
> > diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> > index 3bc29acbd54e..e0987c749ec2 100644
> > --- a/drivers/devfreq/governor_passive.c
> > +++ b/drivers/devfreq/governor_passive.c
> > @@ -99,12 +99,12 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
> >  {
> >  	int ret;
> >  
> > -	if (!devfreq->governor)
> > +	if (!devfreq->policy.governor)
> >  		return -EINVAL;
> >  
> >  	mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
> >  
> > -	ret = devfreq->governor->get_target_freq(devfreq, &freq);
> > +	ret = devfreq->policy.governor->get_target_freq(devfreq, &freq);
> >  	if (ret < 0)
> >  		goto out;
> >  
> > diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> > index 3aae5b3af87c..9bf23b976f4d 100644
> > --- a/include/linux/devfreq.h
> > +++ b/include/linux/devfreq.h
> > @@ -109,6 +109,30 @@ struct devfreq_dev_profile {
> >  	unsigned int max_state;
> >  };
> >  
> > +/**
> > + * struct devfreq_freq_limits - Devfreq frequency limits
> > + * @min_freq:	minimum frequency
> > + * @max_freq:	maximum frequency
> > + */
> > +struct devfreq_freq_limits {
> > +	unsigned long min_freq;
> > +	unsigned long max_freq;
> > +};
> > +
> > +/**
> > + * struct devfreq_policy - Devfreq policy
> > + * @user:	frequency limits requested by the user
> > + * @devinfo:	frequency limits of the device (available OPPs)
> > + * @governor:	method how to choose frequency based on the usage.
> 
> nitpick. remove '.' on the end of line.

Ok

> > + * @governor_name:	devfreq governor name for use with this devfreq
> > + */
> > +struct devfreq_policy {
> > +	struct devfreq_freq_limits user;
> > +	struct devfreq_freq_limits devinfo;
> > +	const struct devfreq_governor *governor;
> > +	char governor_name[DEVFREQ_NAME_LEN];
> > +};
> > +
> >  /**
> >   * struct devfreq - Device devfreq structure
> >   * @node:	list node - contains the devices with devfreq that have been
> > @@ -117,8 +141,6 @@ struct devfreq_dev_profile {
> >   * @dev:	device registered by devfreq class. dev.parent is the device
> >   *		using devfreq.
> >   * @profile:	device-specific devfreq profile
> > - * @governor:	method how to choose frequency based on the usage.
> > - * @governor_name:	devfreq governor name for use with this devfreq
> >   * @nb:		notifier block used to notify devfreq object that it should
> >   *		reevaluate operable frequencies. Devfreq users may use
> >   *		devfreq.nb to the corresponding register notifier call chain.
> > @@ -126,10 +148,7 @@ struct devfreq_dev_profile {
> >   * @previous_freq:	previously configured frequency value.
> >   * @data:	Private data of the governor. The devfreq framework does not
> >   *		touch this.
> > - * @min_freq:	Limit minimum frequency requested by user (0: none)
> > - * @max_freq:	Limit maximum frequency requested by user (0: none)
> > - * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
> > - * @scaling_max_freq:	Limit maximum frequency requested by OPP interface
> > + * @policy:		Policy for frequency adjustments
> 
> The devfreq_policy contains the range of frequency and governor information.
> But, this description focus on the frequency. You need to explain the more
> correct description of 'policy'.

I wouldn't say that the focus is on 'frequency', but on 'frequency
adjustments', and the governor is an integral part of them.

I can change it to "Policy for frequency adjustments, including
frequency limits and the governor" if you prefer. I'm open to other
suggestions.

> >   * @stop_polling:	 devfreq polling status of a device.
> >   * @total_trans:	Number of devfreq transitions
> >   * @trans_table:	Statistics of devfreq transitions
> > @@ -151,8 +170,6 @@ struct devfreq {
> >  	struct mutex lock;
> >  	struct device dev;
> >  	struct devfreq_dev_profile *profile;
> > -	const struct devfreq_governor *governor;
> > -	char governor_name[DEVFREQ_NAME_LEN];
> >  	struct notifier_block nb;
> >  	struct delayed_work work;
> >  
> > @@ -161,10 +178,7 @@ struct devfreq {
> >  
> >  	void *data; /* private data for governors */
> >  
> > -	unsigned long min_freq;
> > -	unsigned long max_freq;
> > -	unsigned long scaling_min_freq;
> > -	unsigned long scaling_max_freq;
> > +	struct devfreq_policy policy;
> 
> I recommend that you better to move under 'struct devfreq_dev_profile'
> as following:
> 	
> 	struct devfreq_dev_profile *profile;
> 	struct devfreq_policy policy;

Will do

Thanks for the review!