Re: [PATCH v9 17/19] PM / devfreq: tegra30: Support variable polling interval

[Chanwoo Choi]

Hi Dmitry,

On 19. 11. 5. ìì 6:56, 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@xxxxxxxxx>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 78 ++++++++++++++++++++++++++-----
>  1 file changed, 66 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 3bd920829bfd..e44f1a48f838 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -171,6 +171,8 @@ struct tegra_devfreq {
>  	struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
>  
>  	unsigned int		irq;
> +
> +	bool			started;
>  };
>  
>  struct tegra_actmon_emc_ratio {
> @@ -209,18 +211,26 @@ static void device_writel(struct tegra_devfreq_device *dev, u32 val,
>  	writel_relaxed(val, dev->regs + offset);
>  }
>  
> -static unsigned long do_percent(unsigned long val, unsigned int pct)
> +static unsigned long do_percent(unsigned long long val, unsigned int pct)
>  {
> -	return val * pct / 100;
> +	val = val * pct;
> +	do_div(val, 100);
> +
> +	/*
> +	 * High freq + high boosting percent + large polling interval are
> +	 * resulting in integer overflow when watermarks are calculated.
> +	 */
> +	return min_t(u64, val, U32_MAX);
>  }
>  
>  static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
>  					   struct tegra_devfreq_device *dev)
>  {
> -	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;
> +	u32 avg;
>  
> +	avg = min(dev->avg_count, U32_MAX - band);
>  	device_writel(dev, avg + band, ACTMON_DEV_AVG_UPPER_WMARK);
>  
>  	avg = max(dev->avg_count, band);
> @@ -230,7 +240,7 @@ 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);
> @@ -309,7 +319,7 @@ 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);
>  
> @@ -469,7 +479,7 @@ 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);
> @@ -505,12 +515,15 @@ static void tegra_actmon_stop_devices(struct tegra_devfreq *tegra)
>  	}
>  }
>  
> -static int tegra_actmon_start(struct tegra_devfreq *tegra)
> +static int tegra_actmon_resume(struct tegra_devfreq *tegra)
>  {
>  	unsigned int i;
>  	int err;
>  
> -	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
> +	if (!tegra->devfreq->profile->polling_ms || !tegra->started)
> +		return 0;
> +
> +	actmon_writel(tegra, tegra->devfreq->profile->polling_ms - 1,
>  		      ACTMON_GLB_PERIOD_CTRL);
>  
>  	/*
> @@ -558,8 +571,26 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
>  	return err;
>  }
>  
> -static void tegra_actmon_stop(struct tegra_devfreq *tegra)
> +static int tegra_actmon_start(struct tegra_devfreq *tegra)
>  {
> +	int ret = 0;
> +
> +	if (!tegra->started) {
> +		tegra->started = true;
> +
> +		ret = tegra_actmon_resume(tegra);
> +		if (ret)
> +			tegra->started = false;
> +	}
> +
> +	return ret;
> +}
> +
> +static void tegra_actmon_pause(struct tegra_devfreq *tegra)
> +{
> +	if (!tegra->devfreq->profile->polling_ms || !tegra->started)
> +		return;
> +
>  	disable_irq(tegra->irq);
>  
>  	cpufreq_unregister_notifier(&tegra->cpu_rate_change_nb,
> @@ -572,6 +603,12 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>  	clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
>  }
>  
> +static void tegra_actmon_stop(struct tegra_devfreq *tegra)
> +{
> +	tegra_actmon_pause(tegra);
> +	tegra->started = false;
> +}
> +
>  static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>  				u32 flags)
>  {
> @@ -629,7 +666,7 @@ 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);
>  
> @@ -637,7 +674,7 @@ 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,
>  };
> @@ -677,6 +714,7 @@ 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;
>  
>  	/*
> @@ -696,6 +734,21 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
>  		devfreq_monitor_stop(devfreq);
>  		break;
>  
> +	case DEVFREQ_GOV_INTERVAL:
> +		/*
> +		 * ACTMON hardware supports up to 256 milliseconds for the
> +		 * sampling period.
> +		 */
> +		if (*new_delay > 256) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		tegra_actmon_pause(tegra);
> +		devfreq_interval_update(devfreq, new_delay);
> +		ret = tegra_actmon_resume(tegra);
> +		break;
> +
>  	case DEVFREQ_GOV_SUSPEND:
>  		tegra_actmon_stop(tegra);
>  		devfreq_monitor_suspend(devfreq);
> @@ -715,6 +768,7 @@ static struct devfreq_governor tegra_devfreq_governor = {
>  	.get_target_freq = tegra_governor_get_target,
>  	.event_handler = tegra_governor_event_handler,
>  	.immutable = true,
> +	.interrupt_driven = true,
>  };
>  
>  static int tegra_devfreq_probe(struct platform_device *pdev)
> 

Reviewed-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics