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Date: Wed, 2 Oct 2019 09:18:31 +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>
Cc: linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 18/19] PM / devfreq: tegra30: Support variable
polling interval
Hi,
On 19. 8. 12. 오전 6:23, 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 | 71 ++++++++++++++++++++++---------
> 1 file changed, 50 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 8adc0ff48b45..e30314bd571a 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -12,6 +12,7 @@
> #include <linux/interrupt.h>
> #include <linux/io.h>
> #include <linux/irq.h>
> +#include <linux/jiffies.h>
> #include <linux/module.h>
> #include <linux/of_device.h>
> #include <linux/platform_device.h>
> @@ -236,7 +237,7 @@ tegra_actmon_dev_avg_dependency_freq(struct tegra_devfreq *tegra,
> struct tegra_devfreq_device *dev)
> {
> return dev->config->avg_dependency_threshold /
> - ACTMON_SAMPLING_PERIOD;
> + tegra->devfreq->profile->polling_ms;
> }
>
> static unsigned long
> @@ -314,8 +315,8 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
> */
> *upper = tegra_actmon_account_cpu_freq(tegra, dev, *upper);
>
> - *lower *= ACTMON_SAMPLING_PERIOD;
> - *upper *= ACTMON_SAMPLING_PERIOD;
> + *lower *= tegra->devfreq->profile->polling_ms;
> + *upper *= tegra->devfreq->profile->polling_ms;
> }
>
> static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
> @@ -341,8 +342,8 @@ static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
> * result, but this one is probably the least churning, although
> * it may look a bit convoluted.
> */
> - if (freq * ACTMON_SAMPLING_PERIOD > upper)
> - upper = freq * ACTMON_SAMPLING_PERIOD;
> + if (freq * tegra->devfreq->profile->polling_ms > upper)
> + upper = freq * tegra->devfreq->profile->polling_ms;
>
> /*
> * We want to get interrupts when MCCPU client crosses the
> @@ -420,7 +421,7 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
> avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
> dev_ctrl = device_readl(dev, ACTMON_DEV_CTRL);
>
> - dev->avg_freq = avg_count / ACTMON_SAMPLING_PERIOD;
> + dev->avg_freq = avg_count / tegra->devfreq->profile->polling_ms;
>
> avg_intr_mask = ACTMON_DEV_INTR_AVG_BELOW_WMARK |
> ACTMON_DEV_INTR_AVG_ABOVE_WMARK;
> @@ -499,7 +500,7 @@ static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
> * outdated.
> */
> avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
> - avg_freq = avg_count / ACTMON_SAMPLING_PERIOD;
> + avg_freq = avg_count / tegra->devfreq->profile->polling_ms;
>
> old_upper = tegra_actmon_upper_freq(tegra, dev->avg_freq);
> new_upper = tegra_actmon_upper_freq(tegra, avg_freq);
> @@ -675,7 +676,7 @@ static int tegra_actmon_cpu_notify_cb(struct notifier_block *nb,
> * here for too long, otherwise CPUFreq's core will complain with a
> * warning splat.
> */
> - delay = msecs_to_jiffies(ACTMON_SAMPLING_PERIOD);
> + delay = msecs_to_jiffies(tegra->devfreq->profile->polling_ms);
> schedule_delayed_work(&tegra->cpufreq_update_work, delay);
>
> return NOTIFY_OK;
> @@ -690,7 +691,7 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
> dev->boost_freq = 0;
>
> dev->avg_freq = clk_get_rate(tegra->emc_clock) / KHZ;
> - device_writel(dev, dev->avg_freq * ACTMON_SAMPLING_PERIOD,
> + device_writel(dev, dev->avg_freq * tegra->devfreq->profile->polling_ms,
> ACTMON_DEV_INIT_AVG);
>
> tegra_devfreq_update_avg_wmark(tegra, dev, dev->avg_freq);
> @@ -725,7 +726,14 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
> unsigned int i;
> int err;
>
> - actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
> + if (!tegra->devfreq->stop_polling)
I don't prefer to change the 'stop_polling' on each device driver direclty
without devfreq interface. Don't access it directly.
> + return 0;
> +
> + tegra->devfreq->previous_freq = clk_get_rate(tegra->emc_clock) / KHZ;
> + tegra->devfreq->last_stat_updated = jiffies;
> + tegra->devfreq->stop_polling = false;
ditto.
> +
> + actmon_writel(tegra, tegra->devfreq->profile->polling_ms - 1,
> ACTMON_GLB_PERIOD_CTRL);
>
> /*
> @@ -776,6 +784,11 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
> {
> unsigned int i;
>
> + if (tegra->devfreq->stop_polling)
ditto.
> + return;
> +
> + mutex_unlock(&tegra->devfreq->lock);
> +
> disable_irq(tegra->irq);
>
> cpufreq_unregister_notifier(&tegra->cpu_rate_change_nb,
> @@ -783,10 +796,16 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>
> cancel_delayed_work_sync(&tegra->cpufreq_update_work);
>
> + mutex_lock(&tegra->devfreq->lock);
> +
> for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
> tegra_actmon_stop_device(&tegra->devices[i]);
>
> clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
> +
> + devfreq_update_status(tegra->devfreq, tegra->devfreq->previous_freq);
> +
> + tegra->devfreq->stop_polling = true;
ditto.
> }
>
> static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
> @@ -846,7 +865,7 @@ 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 = cur_freq * ACTMON_SAMPLING_PERIOD;
> + stat->total_time = cur_freq * tegra->devfreq->profile->polling_ms;
>
> stat->busy_time = min(stat->busy_time, stat->total_time);
>
> @@ -854,7 +873,7 @@ 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,
> };
> @@ -895,8 +914,11 @@ 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, *delay_ptr = data;
> int ret = 0;
>
> + mutex_lock(&devfreq->lock);
> +
> /*
> * Couple device with the governor early as it is needed at
> * the moment of governor's start (used by ISR).
> @@ -905,26 +927,33 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
>
> switch (event) {
> case DEVFREQ_GOV_START:
> - devfreq_monitor_start(devfreq);
> + devfreq->stop_polling = true;
It is not proper to initialize the 'stop_polling' on device driver directly.
> + /* fall through */
> + case DEVFREQ_GOV_RESUME:
> ret = tegra_actmon_start(tegra);
> break;
>
> case DEVFREQ_GOV_STOP:
> - tegra_actmon_stop(tegra);
> - devfreq_monitor_stop(devfreq);
Why do you remove them?
> - break;
> -
> + /* fall through */
> case DEVFREQ_GOV_SUSPEND:
> tegra_actmon_stop(tegra);
> - devfreq_monitor_suspend(devfreq);
Why do you remove it?
> break;
>
> - case DEVFREQ_GOV_RESUME:
> - devfreq_monitor_resume(devfreq);
> - ret = tegra_actmon_start(tegra);
> + case DEVFREQ_GOV_INTERVAL:
> + new_delay = *delay_ptr;
> +
> + if (!new_delay || new_delay > 256) {
> + ret = -EINVAL;
> + } else {
> + tegra_actmon_stop(tegra);
> + devfreq->profile->polling_ms = new_delay;
> + ret = tegra_actmon_start(tegra);
> + }
> break;
> }
>
> + mutex_unlock(&devfreq->lock);
> +
> return ret;
> }
>
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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