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Date: Mon, 4 Nov 2019 11:53:23 +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>,
Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc: linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 16/18] PM / devfreq: tegra30: Support variable
polling interval
On 19. 11. 4. 오전 5:41, 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 | 83 +++++++++++++++++++++++--------
> 1 file changed, 61 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 852bde6249c7..9c645e83ef8b 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -96,9 +96,10 @@ struct tegra_devfreq_device_config {
> unsigned int boost_down_threshold;
>
> /*
> - * Threshold of activity (cycles) below which the CPU frequency isn't
> - * to be taken into account. This is to avoid increasing the EMC
> - * frequency when the CPU is very busy but not accessing the bus often.
> + * Threshold of activity (cycles translated to kHz) below which the
> + * CPU frequency isn't to be taken into account. This is to avoid
> + * increasing the EMC frequency when the CPU is very busy but not
> + * accessing the bus often.
> */
> u32 avg_dependency_threshold;
> };
> @@ -126,7 +127,7 @@ static const struct tegra_devfreq_device_config actmon_device_configs[] = {
> .boost_down_coeff = 90,
> .boost_up_threshold = 27,
> .boost_down_threshold = 10,
> - .avg_dependency_threshold = 50000,
> + .avg_dependency_threshold = 5 * KHZ,
nitpick.
Actually, this change is not related to this patch.
Even if it is trivial, it is not proper.
> },
> };
>
> @@ -208,9 +209,16 @@ 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,
> @@ -218,8 +226,9 @@ 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;
>
> + avg = min(dev->avg_count, U32_MAX - band);
> device_writel(dev, avg + band, ACTMON_DEV_AVG_UPPER_WMARK);
>
> avg = max(dev->avg_count, band);
> @@ -229,7 +238,7 @@ 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);
> @@ -308,10 +317,9 @@ 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;
>
> return target_freq;
> }
> @@ -322,15 +330,18 @@ static void actmon_update_target(struct tegra_devfreq *tegra,
> unsigned long cpu_freq = 0;
> unsigned long static_cpu_emc_freq = 0;
>
> - if (dev->config->avg_dependency_threshold) {
> + dev->target_freq = actmon_device_target_freq(tegra, dev);
> +
> + if (dev->config->avg_dependency_threshold &&
> + dev->config->avg_dependency_threshold <= dev->target_freq) {
This changes are related to polling interval change at the run time?
This patch touched the 'avg_dependency_threshold'. It is related to the
dynamic change of polling interval?
> cpu_freq = cpufreq_quick_get(0);
> static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
> - }
>
> - dev->target_freq = actmon_device_target_freq(tegra, dev);
> -
> - if (dev->avg_count >= dev->config->avg_dependency_threshold)
> + dev->target_freq += dev->boost_freq;
> dev->target_freq = max(dev->target_freq, static_cpu_emc_freq);
> + } else {
> + dev->target_freq += dev->boost_freq;
> + }
ditto. This changes are related to polling interval change at the run time?
> }
>
> static irqreturn_t actmon_thread_isr(int irq, void *data)
> @@ -396,15 +407,16 @@ static unsigned long
> tegra_actmon_cpufreq_contribution(struct tegra_devfreq *tegra,
> unsigned int cpu_freq)
> {
> + struct tegra_devfreq_device *dev = &tegra->devices[MCCPU];
> unsigned long static_cpu_emc_freq, dev_freq;
>
> + dev_freq = actmon_device_target_freq(tegra, dev);
> +
> /* check whether CPU's freq is taken into account at all */
> - if (tegra->devices[MCCPU].avg_count <
> - tegra->devices[MCCPU].config->avg_dependency_threshold)
> + if (dev_freq < dev->config->avg_dependency_threshold)
ditto.
> return 0;
>
> static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
> - dev_freq = actmon_device_target_freq(tegra, &tegra->devices[MCCPU]);
>
> if (dev_freq >= static_cpu_emc_freq)
> return 0;
> @@ -465,7 +477,7 @@ 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 +518,10 @@ 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->cur_freq)
> + return 0;
> +
> + actmon_writel(tegra, tegra->devfreq->profile->polling_ms - 1,
> ACTMON_GLB_PERIOD_CTRL);
>
> /*
> @@ -551,11 +566,16 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
>
> clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
>
> + tegra->cur_freq = 0;
> +
> return err;
> }
>
> static void tegra_actmon_stop(struct tegra_devfreq *tegra)
> {
> + if (!tegra->devfreq->profile->polling_ms || !tegra->cur_freq)
> + return;
> +
> disable_irq(tegra->irq);
>
> cpufreq_unregister_notifier(&tegra->cpu_rate_change_nb,
> @@ -566,6 +586,8 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
> tegra_actmon_stop_devices(tegra);
>
> clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
> +
> + tegra->cur_freq = 0;
> }
>
> static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
> @@ -625,7 +647,7 @@ 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);
>
> @@ -633,7 +655,7 @@ 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,
> };
> @@ -673,6 +695,7 @@ 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;
>
> /*
> @@ -692,6 +715,21 @@ 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_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);
> @@ -711,6 +749,7 @@ 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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