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Message-ID: <5e1246dc-0dce-1f05-49f7-354a581ae510@samsung.com>
Date: Tue, 5 Nov 2019 13:02:22 +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 v9 17/19] PM / devfreq: tegra30: Support variable
polling interval
Hi Dmitry,
On 19. 11. 5. 오전 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@...il.com>
> ---
> 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@...sung.com>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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