Re: [PATCH v7 17/19] PM / devfreq: tegra30: Support variable polling interval

[Dmitry Osipenko <digetx@gmail.com>]

01.11.2019 10:41, Chanwoo Choi пишет:
> On 19. 10. 30. 오전 7:00, Dmitry Osipenko wrote:
>> The ACTMON governor is interrupt-driven and currently hardware's polling
>> interval is fixed to 16ms in the driver. Devfreq supports variable polling
>> interval by the generic governors, let's re-use the generic interface for
>> changing of the polling interval. Now the polling interval can be changed
>> dynamically via /sys/class/devfreq/devfreq0/polling_interval.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 35 ++++++++++++++++++++++++-------
>>  1 file changed, 28 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index b745a973c35a..d0dd42856e5b 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -218,7 +218,7 @@ static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
>>  {
>>  	u32 avg = dev->avg_count;
>>  	u32 avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
>> -	u32 band = avg_band_freq * ACTMON_SAMPLING_PERIOD;
>> +	u32 band = avg_band_freq * tegra->devfreq->profile->polling_ms;
>>  
>>  	device_writel(dev, avg + band, ACTMON_DEV_AVG_UPPER_WMARK);
>>  
>> @@ -229,7 +229,7 @@ static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
>>  static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
>>  				       struct tegra_devfreq_device *dev)
>>  {
>> -	u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
>> +	u32 val = tegra->cur_freq * tegra->devfreq->profile->polling_ms;
>>  
>>  	device_writel(dev, do_percent(val, dev->config->boost_up_threshold),
>>  		      ACTMON_DEV_UPPER_WMARK);
>> @@ -308,7 +308,7 @@ static unsigned long actmon_device_target_freq(struct tegra_devfreq *tegra,
>>  	unsigned int avg_sustain_coef;
>>  	unsigned long target_freq;
>>  
>> -	target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
>> +	target_freq = dev->avg_count / tegra->devfreq->profile->polling_ms;
>>  	avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
>>  	target_freq = do_percent(target_freq, avg_sustain_coef);
>>  	target_freq += dev->boost_freq;
>> @@ -465,7 +465,7 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
>>  
>>  	dev->target_freq = tegra->cur_freq;
>>  
>> -	dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
>> +	dev->avg_count = tegra->cur_freq * tegra->devfreq->profile->polling_ms;
>>  	device_writel(dev, dev->avg_count, ACTMON_DEV_INIT_AVG);
>>  
>>  	tegra_devfreq_update_avg_wmark(tegra, dev);
>> @@ -506,7 +506,11 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
>>  	unsigned int i;
>>  	int err;
>>  
>> -	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
>> +	if (!tegra->devfreq->profile->polling_ms ||
>> +	    tegra->devfreq->stop_polling)
> 
> I think that the access of 'devfreq->stop_polling' is not good
> on governor. It is possible to alter with DEVFREQ_GOV_START/STOP/SUSPEND/RESUME
> notification.

Could you please clarify what you're meaning by "alter with notification"?

Do you mean to have the start/stop state tracking done by the
tegra30-devfreq driver itself?

>> +		return 0;> +
>> +	actmon_writel(tegra, tegra->devfreq->profile->polling_ms - 1,
>>  		      ACTMON_GLB_PERIOD_CTRL);
>>  
>>  	/*
>> @@ -554,6 +558,10 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
>>  
>>  static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>>  {
>> +	if (!tegra->devfreq->profile->polling_ms ||
>> +	    tegra->devfreq->stop_polling)
> 
> ditto.
> 
>> +		return;
>> +
>>  	disable_irq(tegra->irq);
>>  
>>  	cpufreq_unregister_notifier(&tegra->cpu_rate_change_nb,
>> @@ -623,7 +631,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
>>  	stat->busy_time *= 100 / BUS_SATURATION_RATIO;
>>  
>>  	/* Number of cycles in a sampling period */
>> -	stat->total_time = ACTMON_SAMPLING_PERIOD * cur_freq;
>> +	stat->total_time = tegra->devfreq->profile->polling_ms * cur_freq;
>>  
>>  	stat->busy_time = min(stat->busy_time, stat->total_time);
>>  
>> @@ -631,7 +639,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
>>  }
>>  
>>  static struct devfreq_dev_profile tegra_devfreq_profile = {
>> -	.polling_ms	= 0,
>> +	.polling_ms	= ACTMON_SAMPLING_PERIOD,
>>  	.target		= tegra_devfreq_target,
>>  	.get_dev_status	= tegra_devfreq_get_dev_status,
>>  };
>> @@ -671,6 +679,7 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
>>  					unsigned int event, void *data)
>>  {
>>  	struct tegra_devfreq *tegra = dev_get_drvdata(devfreq->dev.parent);
>> +	unsigned int *new_delay = data;
>>  	int ret = 0;
>>  
>>  	/*
>> @@ -690,6 +699,17 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
>>  		devfreq_monitor_stop(devfreq);
>>  		break;
>>  
>> +	case DEVFREQ_GOV_INTERVAL:
>> +		if (*new_delay > 256) {
> 
> Need to add the comment why the maximum delay is under 256 ms.

Okay, will add comment in v8. The 256ms max is the hardware's capability.