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Date: Fri, 1 Nov 2019 16:41:57 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Dmitry Osipenko <digetx@...il.com>,
Thierry Reding <thierry.reding@...il.com>,
MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Tomeu Vizoso <tomeu.vizoso@...labora.com>,
Peter Geis <pgwipeout@...il.com>
Cc: linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 17/19] PM / devfreq: tegra30: Support variable
polling interval
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@...il.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.
> + 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.
> + ret = -EINVAL;
> + break;
> + }
> +
> + tegra_actmon_stop(tegra);
> + devfreq_interval_update(devfreq, new_delay);
> + ret = tegra_actmon_start(tegra);
> + break;
> +
> case DEVFREQ_GOV_SUSPEND:
> tegra_actmon_stop(tegra);
> devfreq_monitor_suspend(devfreq);
> @@ -709,6 +729,7 @@ 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)
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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