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More improvements for Tegra30 devfreq driver

PATCH Superseded Dmitry Osipenko 2 participants 25 messages Jun 27, 2019 – Jun 28, 2019

Subsystems (4)

v3 of 9 Superseded Latest is v9 →

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Dmitry Osipenko

author maintainer
#0 lore raw

v3 cover More improvements for Tegra30 devfreq driver

Hello,

This series addresses some additional review comments that were made by Thierry Reding to [1] and makes several important changes to the driver, fixing excessive interrupts activity. In the end I'm proposing myself as a maintainer for the Tegra devfreq drivers.

[1] https://lore.kernel.org/lkml/[email protected]/T/

Changelog:

v3: Added support for tracepoints, replacing the debug messages.
Fixed few more bugs with the help of tracepoints.

New patches in this version:

PM / devfreq: tegra30: Use tracepoints for debugging
PM / devfreq: tegra30: Optimize CPUFreq notifier
PM / devfreq: tegra30: Optimize upper consecutive watermark selection PM / devfreq: tegra30: Optimize upper average watermark selection PM / devfreq: tegra30: Include appropriate header

Some of older patches of this series also got some extra minor polish.

v2: Added more patches that are cleaning driver's code further and
squashing another kHz conversion bug.

The patch "Rework frequency management logic" of the v1 series is now converted to "Set up watermarks properly" because I found some problems in the original patch and then realized that there is no need to change the logic much. So the logic mostly preserved and only got improvements.

The series is based on the today's linux-next (25 Jun) and takes into account minor changes that MyungJoo Ham made to the already queued patches from the first batch [1].

Dmitry Osipenko (22):
PM / devfreq: tegra30: Change irq type to unsigned int
PM / devfreq: tegra30: Keep interrupt disabled while governor is
stopped
PM / devfreq: tegra30: Handle possible round-rate error
PM / devfreq: tegra30: Drop write-barrier
PM / devfreq: tegra30: Set up watermarks properly
PM / devfreq: tegra30: Tune up boosting thresholds
PM / devfreq: tegra30: Use CPUFreq notifier
PM / devfreq: tegra30: Move clk-notifier's registration to governor's
start
PM / devfreq: tegra30: Reset boosting on startup
PM / devfreq: tegra30: Don't enable consecutive-down interrupt on
startup
PM / devfreq: tegra30: Add debug messages
PM / devfreq: tegra30: Inline all one-line functions
PM / devfreq: tegra30: Constify structs
PM / devfreq: tegra30: Ensure that target freq won't overflow PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out PM / devfreq: tegra30: Use kHz units uniformly in the code PM / devfreq: tegra30: Use tracepoints for debugging
PM / devfreq: tegra30: Optimize CPUFreq notifier
PM / devfreq: tegra30: Optimize upper consecutive watermark selection PM / devfreq: tegra30: Optimize upper average watermark selection PM / devfreq: tegra30: Include appropriate header
PM / devfreq: tegra20/30: Add Dmitry as a maintainer

 MAINTAINERS                            |   9 +
 drivers/devfreq/tegra30-devfreq.c      | 631 ++++++++++++++++++-------
 include/trace/events/tegra30_devfreq.h | 105 ++++
 3 files changed, 583 insertions(+), 162 deletions(-)
 create mode 100644 include/trace/events/tegra30_devfreq.h
Signature · 1 line
2.22.0
author maintainer
#1 lore raw

PATCH v3 1/22 PM / devfreq: tegra30: Change irq type to unsigned int

IRQ numbers are always positive, hence the corresponding variable should be unsigned to keep types consistent. This is a minor change that cleans up code a tad more.

---
 drivers/devfreq/tegra30-devfreq.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
drivers/devfreq/tegra30-devfreq.c +4 -4
index a6ba75f4106d..a27300f40b0b 100644
@@ -160,7 +160,7 @@ struct tegra_devfreq {
 
 	struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
 
-	int irq;
+	unsigned int		irq;
 };
 
 struct tegra_actmon_emc_ratio {
@@ -618,12 +618,12 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		return PTR_ERR(tegra->emc_clock);
 	}
 
-	tegra->irq = platform_get_irq(pdev, 0);
-	if (tegra->irq < 0) {
-		err = tegra->irq;
+	err = platform_get_irq(pdev, 0);
+	if (err < 0) {
 		dev_err(&pdev->dev, "Failed to get IRQ: %d\n", err);
 		return err;
 	}
+	tegra->irq = err;
 
 	reset_control_assert(tegra->reset);
 
Signature · 1 line
2.22.0
author maintainer
#2 lore raw

PATCH v3 2/22 PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped

In reply to Dmitry Osipenko

There is no real need to keep interrupt always-enabled, will be nicer to keep it disabled while governor is inactive.

---
 drivers/devfreq/tegra30-devfreq.c | 43 ++++++++++++++++---------------
 1 file changed, 22 insertions(+), 21 deletions(-)
drivers/devfreq/tegra30-devfreq.c +22 -21
index a27300f40b0b..5e2b133babdd 100644
@@ -11,6 +11,7 @@
 #include <linux/devfreq.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
@@ -416,8 +417,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
 {
 	unsigned int i;
 
-	disable_irq(tegra->irq);
-
 	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
 		      ACTMON_GLB_PERIOD_CTRL);
 
@@ -442,8 +441,6 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
 	}
 
 	actmon_write_barrier(tegra);
-
-	enable_irq(tegra->irq);
 }
 
 static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
@@ -552,6 +549,12 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
 {
 	struct tegra_devfreq *tegra = dev_get_drvdata(devfreq->dev.parent);
 
+	/*
+	 * Couple device with the governor early as it is needed at
+	 * the moment of governor's start (used by ISR).
+	 */
+	tegra->devfreq = devfreq;
+
 	switch (event) {
 	case DEVFREQ_GOV_START:
 		devfreq_monitor_start(devfreq);
@@ -586,10 +589,11 @@ static struct devfreq_governor tegra_devfreq_governor = {
 
 static int tegra_devfreq_probe(struct platform_device *pdev)
 {
-	struct tegra_devfreq *tegra;
 	struct tegra_devfreq_device *dev;
-	unsigned int i;
+	struct tegra_devfreq *tegra;
+	struct devfreq *devfreq;
 	unsigned long rate;
+	unsigned int i;
 	int err;
 
 	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
@@ -625,6 +629,16 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	}
 	tegra->irq = err;
 
+	irq_set_status_flags(tegra->irq, IRQ_NOAUTOEN);
+
+	err = devm_request_threaded_irq(&pdev->dev, tegra->irq, NULL,
+					actmon_thread_isr, IRQF_ONESHOT,
+					"tegra-devfreq", tegra);
+	if (err) {
+		dev_err(&pdev->dev, "Interrupt request failed: %d\n", err);
+		return err;
+	}
+
 	reset_control_assert(tegra->reset);
 
 	err = clk_prepare_enable(tegra->clock);
@@ -672,28 +686,15 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	}
 
 	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
-	tegra->devfreq = devfreq_add_device(&pdev->dev,
-					    &tegra_devfreq_profile,
-					    "tegra_actmon",
-					    NULL);
+	devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile,
+				     "tegra_actmon", NULL);
 	if (IS_ERR(tegra->devfreq)) {
 		err = PTR_ERR(tegra->devfreq);
 		goto remove_governor;
 	}
 
-	err = devm_request_threaded_irq(&pdev->dev, tegra->irq, NULL,
-					actmon_thread_isr, IRQF_ONESHOT,
-					"tegra-devfreq", tegra);
-	if (err) {
-		dev_err(&pdev->dev, "Interrupt request failed: %d\n", err);
-		goto remove_devfreq;
-	}
-
 	return 0;
 
-remove_devfreq:
-	devfreq_remove_device(tegra->devfreq);
-
 remove_governor:
 	devfreq_remove_governor(&tegra_devfreq_governor);
 
Signature · 1 line
2.22.0
maintainer
#3 lore raw

RE: [PATCH v3 02/22] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped

drivers/devfreq/tegra30-devfreq.c

Quoted 13 lines

There is no real need to keep interrupt always-enabled, will be nicer to keep it disabled while governor is inactive.

---
drivers/devfreq/tegra30-devfreq.c | 43 ++++++++++++++++---------------

1 file changed, 22 insertions(+), 21 deletions(-)
drivers/devfreq/tegra30-devfreq.c +0 -0
index a27300f40b0b..5e2b133babdd 100644

[]

drivers/devfreq/tegra30-devfreq.c static void tegra_actmon_start(struct tegra_devfreq *tegra) · line 422

Quoted 9 lines
drivers/devfreq/tegra30-devfreq.c +0 -2
@@ -416,8 +417,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
 {
 	unsigned int i;
 
-	disable_irq(tegra->irq);
-
 	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
 		      ACTMON_GLB_PERIOD_CTRL);
 

I think this has nothing to do with
"keep it disabled while governor is inactive."

And this looks dangerous because it disables the safety measure of disabling interrupt while you touch some looking-critical registers. Anyway, as I do not know the internals of Tegra SoC, I cannot sure.

Cheers,
MyungJoo

author maintainer
#4 lore raw

Re: [PATCH v3 02/22] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped

28.06.2019 9:48, MyungJoo Ham пишет:

Quoted 27 lines

drivers/devfreq/tegra30-devfreq.c

Quoted 13 lines

There is no real need to keep interrupt always-enabled, will be nicer to keep it disabled while governor is inactive.

---
drivers/devfreq/tegra30-devfreq.c | 43 ++++++++++++++++---------------

1 file changed, 22 insertions(+), 21 deletions(-)
drivers/devfreq/tegra30-devfreq.c +0 -0
index a27300f40b0b..5e2b133babdd 100644

[]

drivers/devfreq/tegra30-devfreq.c static void tegra_actmon_start(struct tegra_devfreq *tegra) · line 422

Quoted 9 lines
drivers/devfreq/tegra30-devfreq.c +0 -2
@@ -416,8 +417,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
 {
 	unsigned int i;
 
-	disable_irq(tegra->irq);
-
 	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
 		      ACTMON_GLB_PERIOD_CTRL);
 

I think this has nothing to do with
"keep it disabled while governor is inactive."

Quoted 3 lines

And this looks dangerous because it disables the safety measure of disabling interrupt while you touch some looking-critical registers. Anyway, as I do not know the internals of Tegra SoC, I cannot sure.

Sorry, I'm not sure what do you mean .. Before this patch we were disabling the interrupt on a start of programming hardware configuration, now we don't needed to disable the interrupt because it is already in the disabled state at that moment since we're now requesting interrupt in the *disabled* state during of the driver's probe using IRQ_NOAUTOEN flag.

author maintainer
#5 lore raw

PATCH v3 3/22 PM / devfreq: tegra30: Handle possible round-rate error

In reply to Dmitry Osipenko

The EMC clock rate rounding technically could fail, hence let's handle the error cases properly.

---
 drivers/devfreq/tegra30-devfreq.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)
drivers/devfreq/tegra30-devfreq.c +15 -2
index 5e2b133babdd..5e606ae3f238 100644
@@ -592,8 +592,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	struct tegra_devfreq_device *dev;
 	struct tegra_devfreq *tegra;
 	struct devfreq *devfreq;
-	unsigned long rate;
 	unsigned int i;
+	long rate;
 	int err;
 
 	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
@@ -650,8 +650,14 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 
 	reset_control_deassert(tegra->reset);
 
-	tegra->max_freq = clk_round_rate(tegra->emc_clock, ULONG_MAX) / KHZ;
+	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
+	if (rate < 0) {
+		dev_err(&pdev->dev, "Failed to round clock rate: %ld\n", rate);
+		return rate;
+	}
+
 	tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
+	tegra->max_freq = rate / KHZ;
 
 	for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
 		dev = tegra->devices + i;
@@ -662,6 +668,13 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
 		rate = clk_round_rate(tegra->emc_clock, rate);
 
+		if (rate < 0) {
+			dev_err(&pdev->dev,
+				"Failed to round clock rate: %ld\n", rate);
+			err = rate;
+			goto remove_opps;
+		}
+
 		err = dev_pm_opp_add(&pdev->dev, rate, 0);
 		if (err) {
 			dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
Signature · 1 line
2.22.0
author maintainer
#6 lore raw

PATCH v3 4/22 PM / devfreq: tegra30: Drop write-barrier

In reply to Dmitry Osipenko

There is no need in a write-barrier now, given that interrupt masking is handled by CPU's GIC now. Hence we know exactly that interrupt won't fire after stopping the devfreq's governor. In other cases we don't care about potential buffering of the writes to hardware and thus there is no need to stall CPU.

---
 drivers/devfreq/tegra30-devfreq.c | 14 --------------
 1 file changed, 14 deletions(-)
drivers/devfreq/tegra30-devfreq.c +0 -14
index 5e606ae3f238..4be7858c33bc 100644
@@ -230,12 +230,6 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 		      ACTMON_DEV_LOWER_WMARK);
 }
 
-static void actmon_write_barrier(struct tegra_devfreq *tegra)
-{
-	/* ensure the update has reached the ACTMON */
-	readl(tegra->regs + ACTMON_GLB_STATUS);
-}
-
 static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
@@ -287,8 +281,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 	device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
 
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
-
-	actmon_write_barrier(tegra);
 }
 
 static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
@@ -376,8 +368,6 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 		tegra_devfreq_update_wmark(tegra, dev);
 	}
 
-	actmon_write_barrier(tegra);
-
 	return NOTIFY_OK;
 }
 
@@ -423,8 +413,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
 		tegra_actmon_configure_device(tegra, &tegra->devices[i]);
 
-	actmon_write_barrier(tegra);
-
 	enable_irq(tegra->irq);
 }
 
@@ -439,8 +427,6 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
 		device_writel(&tegra->devices[i], ACTMON_INTR_STATUS_CLEAR,
 			      ACTMON_DEV_INTR_STATUS);
 	}
-
-	actmon_write_barrier(tegra);
 }
 
 static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
Signature · 1 line
2.22.0
author maintainer
#7 lore raw

PATCH v3 5/22 PM / devfreq: tegra30: Set up watermarks properly

In reply to Dmitry Osipenko

The current implementation is inaccurate and results in very intensive interrupt activity, which neglects the whole idea of polling offload to hardware. The reason of the shortcoming is that watermarks are not set up correctly and this results in ACTMON constantly asking to change freq and then these requests are ignored. The end result of this patch is that there are few hundreds of ACTMON's interrupts instead of tens thousands after few minutes of a working devfreq, meanwhile the transitions activity stays about the same and governor becomes more reactive.

Since watermarks are set precisely correct now, the boosting logic is changed a tad to accommodate the change. The "average sustain coefficient" multiplier is gone now since there is no need to compensate the improper watermarks and EMC frequency-bump happens once boosting hits the upper watermark enough times, depending on the per-device boosting threshold.

---
 drivers/devfreq/tegra30-devfreq.c | 294 +++++++++++++++++++++---------
 1 file changed, 209 insertions(+), 85 deletions(-)
drivers/devfreq/tegra30-devfreq.c +209 -85
index 4be7858c33bc..0c84ea44c1c0 100644
@@ -47,6 +47,8 @@
 
 #define ACTMON_DEV_INTR_CONSECUTIVE_UPPER			BIT(31)
 #define ACTMON_DEV_INTR_CONSECUTIVE_LOWER			BIT(30)
+#define ACTMON_DEV_INTR_AVG_BELOW_WMARK				BIT(25)
+#define ACTMON_DEV_INTR_AVG_ABOVE_WMARK				BIT(24)
 
 #define ACTMON_ABOVE_WMARK_WINDOW				1
 #define ACTMON_BELOW_WMARK_WINDOW				3
@@ -63,9 +65,8 @@
  * ACTMON_AVERAGE_WINDOW_LOG2: default value for @DEV_CTRL_K_VAL, which
  * translates to 2 ^ (K_VAL + 1). ex: 2 ^ (6 + 1) = 128
  */
-#define ACTMON_AVERAGE_WINDOW_LOG2			6
-#define ACTMON_SAMPLING_PERIOD				12 /* ms */
-#define ACTMON_DEFAULT_AVG_BAND				6  /* 1/10 of % */
+#define ACTMON_AVERAGE_WINDOW_LOG2				6
+#define ACTMON_SAMPLING_PERIOD					12 /* ms */
 
 #define KHZ							1000
 
@@ -142,9 +143,6 @@ struct tegra_devfreq_device {
 	 * watermark breaches.
 	 */
 	unsigned long boost_freq;
-
-	/* Optimal frequency calculated from the stats for this device */
-	unsigned long target_freq;
 };
 
 struct tegra_devfreq {
@@ -156,7 +154,6 @@ struct tegra_devfreq {
 
 	struct clk		*emc_clock;
 	unsigned long		max_freq;
-	unsigned long		cur_freq;
 	struct notifier_block	rate_change_nb;
 
 	struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
@@ -205,42 +202,182 @@ static unsigned long do_percent(unsigned long val, unsigned int pct)
 	return val * pct / 100;
 }
 
+static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra)
+{
+	struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
+	unsigned int cpu_freq = cpufreq_get(0);
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) {
+		if (cpu_freq >= ratio->cpu_freq) {
+			if (ratio->emc_freq >= tegra->max_freq)
+				return tegra->max_freq;
+			else
+				return ratio->emc_freq;
+		}
+	}
+
+	return 0;
+}
+
+static unsigned long
+tegra_actmon_account_cpu_freq(struct tegra_devfreq *tegra,
+			      struct tegra_devfreq_device *dev,
+			      unsigned long target_freq)
+{
+	unsigned long static_cpu_emc_freq;
+
+	if (dev->config->avg_dependency_threshold &&
+	    dev->config->avg_dependency_threshold < dev->avg_count) {
+		static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra);
+		target_freq = max(target_freq, static_cpu_emc_freq);
+	}
+
+	return target_freq;
+}
+
+static unsigned long tegra_actmon_lower_freq(struct tegra_devfreq *tegra,
+					     unsigned long target_freq)
+{
+	unsigned long lower = target_freq;
+	struct dev_pm_opp *opp;
+
+	opp = dev_pm_opp_find_freq_floor(tegra->devfreq->dev.parent, &lower);
+	if (IS_ERR(opp))
+		lower = 0;
+	else
+		dev_pm_opp_put(opp);
+
+	return lower;
+}
+
+static unsigned long tegra_actmon_upper_freq(struct tegra_devfreq *tegra,
+					     unsigned long target_freq)
+{
+	unsigned long upper = target_freq + 1;
+	struct dev_pm_opp *opp;
+
+	opp = dev_pm_opp_find_freq_ceil(tegra->devfreq->dev.parent, &upper);
+	if (IS_ERR(opp))
+		upper = ULONG_MAX;
+	else
+		dev_pm_opp_put(opp);
+
+	return upper;
+}
+
+static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
+					 struct tegra_devfreq_device *dev,
+					 unsigned long target_freq,
+					 unsigned long *lower,
+					 unsigned long *upper)
+{
+	/*
+	 * Memory frequencies are guaranteed to have 1MHz granularity
+	 * and thus we need this rounding down to get a proper watermarks
+	 * range in a case where target_freq falls into a range of
+	 * next_possible_opp_freq - 1MHz.
+	 */
+	target_freq = round_down(target_freq, 1000000);
+
+	/* watermarks are set at the borders of the corresponding OPPs */
+	*lower = tegra_actmon_lower_freq(tegra, target_freq);
+	*upper = tegra_actmon_upper_freq(tegra, target_freq);
+
+	*lower /= KHZ;
+	*upper /= KHZ;
+
+	/*
+	 * The upper watermark should take into account CPU's frequency
+	 * because cpu_to_emc_rate() may override the target_freq with
+	 * a higher value and thus upper watermark need to be set up
+	 * accordingly to avoid parasitic upper-events.
+	 */
+	*upper = tegra_actmon_account_cpu_freq(tegra, dev, *upper);
+
+	*lower *= ACTMON_SAMPLING_PERIOD;
+	*upper *= ACTMON_SAMPLING_PERIOD;
+}
+
 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;
+	unsigned long lower, upper, freq;
+
+	freq = dev->avg_count / ACTMON_SAMPLING_PERIOD * KHZ;
+	tegra_actmon_get_lower_upper(tegra, dev, freq, &lower, &upper);
 
-	device_writel(dev, avg + band, ACTMON_DEV_AVG_UPPER_WMARK);
+	/*
+	 * We want to get interrupts when MCCPU client crosses the
+	 * dependency threshold in order to take into / out of account
+	 * the CPU's freq.
+	 */
+	if (lower < dev->config->avg_dependency_threshold &&
+	    upper > dev->config->avg_dependency_threshold) {
+		if (dev->avg_count < dev->config->avg_dependency_threshold)
+			upper = dev->config->avg_dependency_threshold;
+		else
+			lower = dev->config->avg_dependency_threshold;
+	}
 
-	avg = max(dev->avg_count, band);
-	device_writel(dev, avg - band, ACTMON_DEV_AVG_LOWER_WMARK);
+	device_writel(dev, lower, ACTMON_DEV_AVG_LOWER_WMARK);
+	device_writel(dev, upper, ACTMON_DEV_AVG_UPPER_WMARK);
 }
 
 static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
-				       struct tegra_devfreq_device *dev)
+				       struct tegra_devfreq_device *dev,
+				       unsigned long freq)
 {
-	u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
+	unsigned long lower, upper, delta;
+
+	/*
+	 * Boosting logic kicks-in once lower / upper watermark is hit.
+	 * The watermarks are based on the updated EMC rate and the
+	 * average activity.
+	 *
+	 * The higher watermark is set in accordance to the EMC rate
+	 * because we want to set it to the highest mark here and EMC rate
+	 * represents that mark. The consecutive-upper interrupts are
+	 * always enabled and we don't want to receive them if they won't
+	 * do anything useful, hence the upper watermark is capped to maximum.
+	 * Note that the EMC rate is changed once boosting pushed the rate
+	 * too high, in that case boosting-up will be stopped because
+	 * upper watermark is much higher now and it is *important* to
+	 * stop the unwanted interrupts.
+	 */
+	tegra_actmon_get_lower_upper(tegra, dev, freq - 1, &lower, &upper);
+
+	delta = do_percent(upper - lower, dev->config->boost_up_threshold);
+	device_writel(dev, lower + delta, ACTMON_DEV_UPPER_WMARK);
 
-	device_writel(dev, do_percent(val, dev->config->boost_up_threshold),
-		      ACTMON_DEV_UPPER_WMARK);
+	/*
+	 * Meanwhile the lower mark is based on the average value
+	 * because it is the lowest possible consecutive-mark for this
+	 * device. Once that mark is hit and boosting is stopped, the
+	 * interrupt is disabled by ISR.
+	 */
+	freq = dev->avg_count / ACTMON_SAMPLING_PERIOD * KHZ;
+	tegra_actmon_get_lower_upper(tegra, dev, freq, &lower, &upper);
 
-	device_writel(dev, do_percent(val, dev->config->boost_down_threshold),
-		      ACTMON_DEV_LOWER_WMARK);
+	delta = do_percent(upper - lower, dev->config->boost_down_threshold);
+	device_writel(dev, lower + delta, ACTMON_DEV_LOWER_WMARK);
 }
 
 static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
-	u32 intr_status, dev_ctrl;
+	u32 intr_status, dev_ctrl, avg_intr_mask;
 
 	dev->avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
-	tegra_devfreq_update_avg_wmark(tegra, dev);
-
 	intr_status = device_readl(dev, ACTMON_DEV_INTR_STATUS);
 	dev_ctrl = device_readl(dev, ACTMON_DEV_CTRL);
 
+	avg_intr_mask = ACTMON_DEV_INTR_AVG_BELOW_WMARK |
+			ACTMON_DEV_INTR_AVG_ABOVE_WMARK;
+
+	if (intr_status & avg_intr_mask)
+		tegra_devfreq_update_avg_wmark(tegra, dev);
+
 	if (intr_status & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) {
 		/*
 		 * new_boost = min(old_boost * up_coef + step, max_freq)
@@ -253,8 +390,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 
 		if (dev->boost_freq >= tegra->max_freq)
 			dev->boost_freq = tegra->max_freq;
-		else
-			dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
 	} else if (intr_status & ACTMON_DEV_INTR_CONSECUTIVE_LOWER) {
 		/*
 		 * new_boost = old_boost * down_coef
@@ -263,63 +398,36 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 		dev->boost_freq = do_percent(dev->boost_freq,
 					     dev->config->boost_down_coeff);
 
-		dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
-
 		if (dev->boost_freq < (ACTMON_BOOST_FREQ_STEP >> 1))
 			dev->boost_freq = 0;
-		else
-			dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
 	}
 
-	if (dev->config->avg_dependency_threshold) {
-		if (dev->avg_count >= dev->config->avg_dependency_threshold)
-			dev_ctrl |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
-		else if (dev->boost_freq == 0)
-			dev_ctrl &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
+	if (intr_status & avg_intr_mask) {
+		/*
+		 * Once average watermark is hit, it means that the memory
+		 * activity changed significantly and thus boosting-up shall
+		 * be reset because EMC clock rate will be changed and
+		 * boosting will restart in this case.
+		 */
+		dev->boost_freq = 0;
 	}
 
-	device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
+	/* no boosting => no need for consecutive-down interrupt */
+	if (dev->boost_freq == 0)
+		dev_ctrl &= ~ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
 
+	device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
 }
 
-static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
-					    unsigned long cpu_freq)
-{
-	unsigned int i;
-	struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
-
-	for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) {
-		if (cpu_freq >= ratio->cpu_freq) {
-			if (ratio->emc_freq >= tegra->max_freq)
-				return tegra->max_freq;
-			else
-				return ratio->emc_freq;
-		}
-	}
-
-	return 0;
-}
-
-static void actmon_update_target(struct tegra_devfreq *tegra,
-				 struct tegra_devfreq_device *dev)
-{
-	unsigned long cpu_freq = 0;
-	unsigned long static_cpu_emc_freq = 0;
-	unsigned int avg_sustain_coef;
-
-	if (dev->config->avg_dependency_threshold) {
-		cpu_freq = cpufreq_get(0);
-		static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
-	}
+static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
+					  struct tegra_devfreq_device *dev)
+{	unsigned long target_freq;
 
-	dev->target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
-	avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
-	dev->target_freq = do_percent(dev->target_freq, avg_sustain_coef);
-	dev->target_freq += dev->boost_freq;
+	target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq;
+	target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);
 
-	if (dev->avg_count >= dev->config->avg_dependency_threshold)
-		dev->target_freq = max(dev->target_freq, static_cpu_emc_freq);
+	return target_freq;
 }
 
 static irqreturn_t actmon_thread_isr(int irq, void *data)
@@ -351,8 +459,8 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 				       unsigned long action, void *ptr)
 {
 	struct clk_notifier_data *data = ptr;
-	struct tegra_devfreq *tegra;
 	struct tegra_devfreq_device *dev;
+	struct tegra_devfreq *tegra;
 	unsigned int i;
 
 	if (action != POST_RATE_CHANGE)
@@ -360,12 +468,28 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 
 	tegra = container_of(nb, struct tegra_devfreq, rate_change_nb);
 
-	tegra->cur_freq = data->new_rate / KHZ;
-
+	/*
+	 * EMC rate could change due to three reasons:
+	 *
+	 *    1. Average watermark hit
+	 *    2. Boosting overflow
+	 *    3. CPU freq change
+	 *
+	 * Once rate is changed, the consecutive watermarks need to be
+	 * updated in order for boosting to work properly and to avoid
+	 * unnecessary interrupts. Note that the consecutive range is set for
+	 * all of devices using the same rate, hence if CPU is doing much
+	 * less than the other memory clients, then its upper watermark will
+	 * be very high in comparison to the actual activity (lower watermark)
+	 * and thus unnecessary upper-interrupts will be suppressed.
+	 *
+	 * The average watermarks also should be updated because of 3.
+	 */
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
 		dev = &tegra->devices[i];
 
-		tegra_devfreq_update_wmark(tegra, dev);
+		tegra_devfreq_update_avg_wmark(tegra, dev);
+		tegra_devfreq_update_wmark(tegra, dev, data->new_rate);
 	}
 
 	return NOTIFY_OK;
@@ -374,15 +498,14 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 					  struct tegra_devfreq_device *dev)
 {
-	u32 val = 0;
-
-	dev->target_freq = tegra->cur_freq;
+	u32 val = 0, target_freq;
 
-	dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
+	target_freq = clk_get_rate(tegra->emc_clock) / KHZ;
+	dev->avg_count = target_freq * ACTMON_SAMPLING_PERIOD;
 	device_writel(dev, dev->avg_count, ACTMON_DEV_INIT_AVG);
 
 	tegra_devfreq_update_avg_wmark(tegra, dev);
-	tegra_devfreq_update_wmark(tegra, dev);
+	tegra_devfreq_update_wmark(tegra, dev, target_freq);
 
 	device_writel(dev, ACTMON_COUNT_WEIGHT, ACTMON_DEV_COUNT_WEIGHT);
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
@@ -469,13 +592,13 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
 	struct tegra_devfreq_device *actmon_dev;
 	unsigned long cur_freq;
 
-	cur_freq = READ_ONCE(tegra->cur_freq);
+	cur_freq = clk_get_rate(tegra->emc_clock);
 
 	/* To be used by the tegra governor */
 	stat->private_data = tegra;
 
 	/* The below are to be used by the other governors */
-	stat->current_frequency = cur_freq * KHZ;
+	stat->current_frequency = cur_freq;
 
 	actmon_dev = &tegra->devices[MCALL];
 
@@ -486,7 +609,7 @@ 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 = cur_freq / KHZ * ACTMON_SAMPLING_PERIOD;
 
 	stat->busy_time = min(stat->busy_time, stat->total_time);
 
@@ -505,6 +628,7 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
 	struct devfreq_dev_status *stat;
 	struct tegra_devfreq *tegra;
 	struct tegra_devfreq_device *dev;
+	unsigned long dev_target_freq;
 	unsigned long target_freq = 0;
 	unsigned int i;
 	int err;
@@ -520,9 +644,9 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
 		dev = &tegra->devices[i];
 
-		actmon_update_target(tegra, dev);
+		dev_target_freq = actmon_update_target(tegra, dev);
 
-		target_freq = max(target_freq, dev->target_freq);
+		target_freq = max(target_freq, dev_target_freq);
 	}
 
 	*freq = target_freq * KHZ;
@@ -642,7 +766,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		return rate;
 	}
 
-	tegra->cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
 	tegra->max_freq = rate / KHZ;
 
 	for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
@@ -671,7 +794,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, tegra);
 
 	tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
-	err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
+	err = clk_notifier_register(tegra->emc_clock,
+				    &tegra->rate_change_nb);
 	if (err) {
 		dev_err(&pdev->dev,
 			"Failed to register rate change notifier\n");
Signature · 1 line
2.22.0
author maintainer
#8 lore raw

PATCH v3 6/22 PM / devfreq: tegra30: Tune up boosting thresholds

In reply to Dmitry Osipenko

Now that average-sustain coefficient / multiplier is gone, it won't hurt to re-tune the boosting thresholds to get a bit harder boosting for MCALL clients, resulting in a more reactive governing in a case of multimedia applications usage like 3d / video.

---
 drivers/devfreq/tegra30-devfreq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/devfreq/tegra30-devfreq.c +2 -2
index 0c84ea44c1c0..7662e54f0e70 100644
@@ -111,8 +111,8 @@ static struct tegra_devfreq_device_config actmon_device_configs[] = {
 		.irq_mask = 1 << 26,
 		.boost_up_coeff = 200,
 		.boost_down_coeff = 50,
-		.boost_up_threshold = 60,
-		.boost_down_threshold = 40,
+		.boost_up_threshold = 50,
+		.boost_down_threshold = 25,
 	},
 	{
 		/* MCCPU: memory accesses from the CPUs */
Signature · 1 line
2.22.0
author maintainer
#9 lore raw

PATCH v3 7/22 PM / devfreq: tegra30: Use CPUFreq notifier

In reply to Dmitry Osipenko

The CPU's client need to take into account that CPUFreq may change while memory activity not, staying high. Thus an appropriate frequency notifier should be used in addition to the clk-notifier.

---
 drivers/devfreq/tegra30-devfreq.c | 105 +++++++++++++++++++++++++-----
 1 file changed, 88 insertions(+), 17 deletions(-)
drivers/devfreq/tegra30-devfreq.c +88 -17
index 7662e54f0e70..502511ac4602 100644
@@ -17,6 +17,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/reset.h>
+#include <linux/workqueue.h>
 
 #include "governor.h"
 
@@ -154,7 +155,10 @@ struct tegra_devfreq {
 
 	struct clk		*emc_clock;
 	unsigned long		max_freq;
-	struct notifier_block	rate_change_nb;
+	struct notifier_block	clk_rate_change_nb;
+
+	struct work_struct	update_work;
+	struct notifier_block	cpu_rate_change_nb;
 
 	struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
 
@@ -455,8 +459,8 @@ static irqreturn_t actmon_thread_isr(int irq, void *data)
 	return handled ? IRQ_HANDLED : IRQ_NONE;
 }
 
-static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
-				       unsigned long action, void *ptr)
+static int tegra_actmon_clk_notify_cb(struct notifier_block *nb,
+				      unsigned long action, void *ptr)
 {
 	struct clk_notifier_data *data = ptr;
 	struct tegra_devfreq_device *dev;
@@ -466,7 +470,7 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 	if (action != POST_RATE_CHANGE)
 		return NOTIFY_OK;
 
-	tegra = container_of(nb, struct tegra_devfreq, rate_change_nb);
+	tegra = container_of(nb, struct tegra_devfreq, clk_rate_change_nb);
 
 	/*
 	 * EMC rate could change due to three reasons:
@@ -495,6 +499,37 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
+static void tegra_actmon_delayed_update(struct work_struct *work)
+{
+	struct tegra_devfreq *tegra = container_of(work, struct tegra_devfreq,
+						   update_work);
+
+	mutex_lock(&tegra->devfreq->lock);
+	update_devfreq(tegra->devfreq);
+	mutex_unlock(&tegra->devfreq->lock);
+}
+
+static int tegra_actmon_cpu_notify_cb(struct notifier_block *nb,
+				      unsigned long action, void *ptr)
+{
+	struct tegra_devfreq *tegra;
+
+	if (action != CPUFREQ_POSTCHANGE)
+		return NOTIFY_OK;
+
+	tegra = container_of(nb, struct tegra_devfreq, cpu_rate_change_nb);
+
+	/*
+	 * CPUFreq driver should support CPUFREQ_ASYNC_NOTIFICATION in order
+	 * to allow asynchronous notifications. This means we can't block
+	 * here for too long, otherwise CPUFreq's core will complain with a
+	 * warning splat.
+	 */
+	schedule_work(&tegra->update_work);
+
+	return NOTIFY_OK;
+}
+
 static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 					  struct tegra_devfreq_device *dev)
 {
@@ -526,9 +561,16 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 	device_writel(dev, val, ACTMON_DEV_CTRL);
 }
 
-static void tegra_actmon_start(struct tegra_devfreq *tegra)
+static void tegra_actmon_stop_device(struct tegra_devfreq_device *dev)
+{
+	device_writel(dev, 0x00000000, ACTMON_DEV_CTRL);
+	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
+}
+
+static int tegra_actmon_start(struct tegra_devfreq *tegra)
 {
 	unsigned int i;
+	int err;
 
 	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
 		      ACTMON_GLB_PERIOD_CTRL);
@@ -536,7 +578,30 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
 		tegra_actmon_configure_device(tegra, &tegra->devices[i]);
 
+	/*
+	 * We are estimating CPU's memory bandwidth requirement based on
+	 * amount of memory accesses and system's load, judging by CPU's
+	 * frequency. We also don't want to receive events about CPU's
+	 * frequency transaction when governor is stopped, hence notifier
+	 * is registered dynamically.
+	 */
+	err = cpufreq_register_notifier(&tegra->cpu_rate_change_nb,
+					CPUFREQ_TRANSITION_NOTIFIER);
+	if (err) {
+		dev_err(tegra->devfreq->dev.parent,
+			"Failed to register rate change notifier: %d\n", err);
+		goto err_stop;
+	}
+
 	enable_irq(tegra->irq);
+
+	return 0;
+
+err_stop:
+	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
+		tegra_actmon_stop_device(&tegra->devices[i]);
+
+	return err;
 }
 
 static void tegra_actmon_stop(struct tegra_devfreq *tegra)
@@ -545,11 +610,13 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
 
 	disable_irq(tegra->irq);
 
-	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
-		device_writel(&tegra->devices[i], 0x00000000, ACTMON_DEV_CTRL);
-		device_writel(&tegra->devices[i], ACTMON_INTR_STATUS_CLEAR,
-			      ACTMON_DEV_INTR_STATUS);
-	}
+	cpufreq_unregister_notifier(&tegra->cpu_rate_change_nb,
+				    CPUFREQ_TRANSITION_NOTIFIER);
+
+	cancel_work_sync(&tegra->update_work);
+
+	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
+		tegra_actmon_stop_device(&tegra->devices[i]);
 }
 
 static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
@@ -658,6 +725,7 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
 					unsigned int event, void *data)
 {
 	struct tegra_devfreq *tegra = dev_get_drvdata(devfreq->dev.parent);
+	int ret = 0;
 
 	/*
 	 * Couple device with the governor early as it is needed at
@@ -668,7 +736,7 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
 	switch (event) {
 	case DEVFREQ_GOV_START:
 		devfreq_monitor_start(devfreq);
-		tegra_actmon_start(tegra);
+		ret = tegra_actmon_start(tegra);
 		break;
 
 	case DEVFREQ_GOV_STOP:
@@ -683,11 +751,11 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
 
 	case DEVFREQ_GOV_RESUME:
 		devfreq_monitor_resume(devfreq);
-		tegra_actmon_start(tegra);
+		ret = tegra_actmon_start(tegra);
 		break;
 	}
 
-	return 0;
+	return ret;
 }
 
 static struct devfreq_governor tegra_devfreq_governor = {
@@ -793,9 +861,12 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, tegra);
 
-	tegra->rate_change_nb.notifier_call = tegra_actmon_rate_notify_cb;
+	tegra->cpu_rate_change_nb.notifier_call = tegra_actmon_cpu_notify_cb;
+	INIT_WORK(&tegra->update_work, tegra_actmon_delayed_update);
+
+	tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
 	err = clk_notifier_register(tegra->emc_clock,
-				    &tegra->rate_change_nb);
+				    &tegra->clk_rate_change_nb);
 	if (err) {
 		dev_err(&pdev->dev,
 			"Failed to register rate change notifier\n");
@@ -822,7 +893,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	devfreq_remove_governor(&tegra_devfreq_governor);
 
 unreg_notifier:
-	clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
+	clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
 
 remove_opps:
 	dev_pm_opp_remove_all_dynamic(&pdev->dev);
@@ -840,7 +911,7 @@ static int tegra_devfreq_remove(struct platform_device *pdev)
 	devfreq_remove_device(tegra->devfreq);
 	devfreq_remove_governor(&tegra_devfreq_governor);
 
-	clk_notifier_unregister(tegra->emc_clock, &tegra->rate_change_nb);
+	clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
 	dev_pm_opp_remove_all_dynamic(&pdev->dev);
 
 	reset_control_reset(tegra->reset);
Signature · 1 line
2.22.0
author maintainer
#10 lore raw

PATCH v3 8/22 PM / devfreq: tegra30: Move clk-notifier's registration to governor's start

In reply to Dmitry Osipenko

There is no point in receiving of the notifications while governor is stopped, let's keep them disabled like we do for the CPU freq-change notifications. This also fixes a potential use-after-free bug if notification happens after device's removal.

---
 drivers/devfreq/tegra30-devfreq.c | 33 ++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 14 deletions(-)
drivers/devfreq/tegra30-devfreq.c +19 -14
index 502511ac4602..1751d17f9a1c 100644
@@ -575,6 +575,19 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
 	actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
 		      ACTMON_GLB_PERIOD_CTRL);
 
+	/*
+	 * CLK notifications are needed in order to reconfigure the upper
+	 * consecutive watermark in accordance to the actual clock rate
+	 * to avoid unnecessary upper interrupts.
+	 */
+	err = clk_notifier_register(tegra->emc_clock,
+				    &tegra->clk_rate_change_nb);
+	if (err) {
+		dev_err(tegra->devfreq->dev.parent,
+			"Failed to register rate change notifier\n");
+		return err;
+	}
+
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
 		tegra_actmon_configure_device(tegra, &tegra->devices[i]);
 
@@ -601,6 +614,8 @@ static int tegra_actmon_start(struct tegra_devfreq *tegra)
 	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);
+
 	return err;
 }
 
@@ -617,6 +632,8 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
 
 	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);
 }
 
 static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
@@ -861,22 +878,14 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, tegra);
 
+	tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
 	tegra->cpu_rate_change_nb.notifier_call = tegra_actmon_cpu_notify_cb;
 	INIT_WORK(&tegra->update_work, tegra_actmon_delayed_update);
 
-	tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
-	err = clk_notifier_register(tegra->emc_clock,
-				    &tegra->clk_rate_change_nb);
-	if (err) {
-		dev_err(&pdev->dev,
-			"Failed to register rate change notifier\n");
-		goto remove_opps;
-	}
-
 	err = devfreq_add_governor(&tegra_devfreq_governor);
 	if (err) {
 		dev_err(&pdev->dev, "Failed to add governor: %d\n", err);
-		goto unreg_notifier;
+		goto remove_opps;
 	}
 
 	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
@@ -892,9 +901,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 remove_governor:
 	devfreq_remove_governor(&tegra_devfreq_governor);
 
-unreg_notifier:
-	clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
-
 remove_opps:
 	dev_pm_opp_remove_all_dynamic(&pdev->dev);
 
@@ -911,7 +917,6 @@ static int tegra_devfreq_remove(struct platform_device *pdev)
 	devfreq_remove_device(tegra->devfreq);
 	devfreq_remove_governor(&tegra_devfreq_governor);
 
-	clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
 	dev_pm_opp_remove_all_dynamic(&pdev->dev);
 
 	reset_control_reset(tegra->reset);
Signature · 1 line
2.22.0
author maintainer
#11 lore raw

PATCH v3 9/22 PM / devfreq: tegra30: Reset boosting on startup

In reply to Dmitry Osipenko

Governor could be stopped while boosting is active. We have assumption that everything is reset on governor's restart, including the boosting value, which was missed.

---
 drivers/devfreq/tegra30-devfreq.c | 3 +++
 1 file changed, 3 insertions(+)
drivers/devfreq/tegra30-devfreq.c +3 -0
index 1751d17f9a1c..cca2fc15bafe 100644
@@ -535,6 +535,9 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 {
 	u32 val = 0, target_freq;
 
+	/* we don't want boosting on restart */
+	dev->boost_freq = 0;
+
 	target_freq = clk_get_rate(tegra->emc_clock) / KHZ;
 	dev->avg_count = target_freq * ACTMON_SAMPLING_PERIOD;
 	device_writel(dev, dev->avg_count, ACTMON_DEV_INIT_AVG);
Signature · 1 line
2.22.0
author maintainer
#12 lore raw

PATCH v3 10/22 PM / devfreq: tegra30: Don't enable consecutive-down interrupt on startup

In reply to Dmitry Osipenko

The consecutive-down event tells that we should perform frequency de-boosting, but boosting is in a reset state on start and hence the event won't do anything useful for us and it will be just a dummy interrupt request.

---
 drivers/devfreq/tegra30-devfreq.c | 1 -
 1 file changed, 1 deletion(-)
drivers/devfreq/tegra30-devfreq.c +0 -1
index cca2fc15bafe..65f0363dbf1b 100644
@@ -557,7 +557,6 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 		<< ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
 	val |= ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN;
 	val |= ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
-	val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
 	val |= ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
 	val |= ACTMON_DEV_CTRL_ENB;
 
Signature · 1 line
2.22.0
author maintainer
#13 lore raw

PATCH v3 11/22 PM / devfreq: tegra30: Add debug messages

In reply to Dmitry Osipenko

Add debug messages to know about what's happening in hardware and how driver reacts.

---
 drivers/devfreq/tegra30-devfreq.c | 35 +++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
drivers/devfreq/tegra30-devfreq.c +35 -0
index 65f0363dbf1b..47a47be276ee 100644
@@ -41,6 +41,7 @@
 #define ACTMON_DEV_AVG_UPPER_WMARK				0x10
 #define ACTMON_DEV_AVG_LOWER_WMARK				0x14
 #define ACTMON_DEV_COUNT_WEIGHT					0x18
+#define ACTMON_DEV_COUNT					0x1c
 #define ACTMON_DEV_AVG_COUNT					0x20
 #define ACTMON_DEV_INTR_STATUS					0x24
 
@@ -276,6 +277,9 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 					 unsigned long *lower,
 					 unsigned long *upper)
 {
+	struct device *ddev = tegra->devfreq->dev.parent;
+	u32 offset = dev->config->offset;
+
 	/*
 	 * Memory frequencies are guaranteed to have 1MHz granularity
 	 * and thus we need this rounding down to get a proper watermarks
@@ -288,6 +292,9 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 	*lower = tegra_actmon_lower_freq(tegra, target_freq);
 	*upper = tegra_actmon_upper_freq(tegra, target_freq);
 
+	dev_dbg(ddev, "%03x: target_freq %lu lower freq %lu upper freq %lu\n",
+		offset, target_freq, *lower, *upper);
+
 	*lower /= KHZ;
 	*upper /= KHZ;
 
@@ -367,11 +374,31 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 	device_writel(dev, lower + delta, ACTMON_DEV_LOWER_WMARK);
 }
 
+static void actmon_device_debug(struct tegra_devfreq *tegra,
+				struct tegra_devfreq_device *dev,
+				const char *prefix)
+{
+	dev_dbg(tegra->devfreq->dev.parent,
+		"%03x: %s: 0x%08x 0x%08x a %u %u %u c %u %u %u b %lu cpu %u\n",
+		dev->config->offset, prefix,
+		device_readl(dev, ACTMON_DEV_INTR_STATUS),
+		device_readl(dev, ACTMON_DEV_CTRL),
+		device_readl(dev, ACTMON_DEV_AVG_COUNT),
+		device_readl(dev, ACTMON_DEV_AVG_LOWER_WMARK),
+		device_readl(dev, ACTMON_DEV_AVG_UPPER_WMARK),
+		device_readl(dev, ACTMON_DEV_COUNT),
+		device_readl(dev, ACTMON_DEV_LOWER_WMARK),
+		device_readl(dev, ACTMON_DEV_UPPER_WMARK),
+		dev->boost_freq, cpufreq_get(0));
+}
+
 static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
 	u32 intr_status, dev_ctrl, avg_intr_mask;
 
+	actmon_device_debug(tegra, dev, "isr+");
+
 	dev->avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
 	intr_status = device_readl(dev, ACTMON_DEV_INTR_STATUS);
 	dev_ctrl = device_readl(dev, ACTMON_DEV_CTRL);
@@ -422,6 +449,8 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 
 	device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
+
+	actmon_device_debug(tegra, dev, "isr-");
 }
 
 static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
@@ -711,6 +740,7 @@ static struct devfreq_dev_profile tegra_devfreq_profile = {
 static int tegra_governor_get_target(struct devfreq *devfreq,
 				     unsigned long *freq)
 {
+	struct device *ddev = devfreq->dev.parent;
 	struct devfreq_dev_status *stat;
 	struct tegra_devfreq *tegra;
 	struct tegra_devfreq_device *dev;
@@ -733,6 +763,11 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
 		dev_target_freq = actmon_update_target(tegra, dev);
 
 		target_freq = max(target_freq, dev_target_freq);
+
+		dev_dbg(ddev, "%03x: upd: dev_target_freq %lu\n",
+			dev->config->offset, dev_target_freq);
+
+		actmon_device_debug(tegra, dev, "upd");
 	}
 
 	*freq = target_freq * KHZ;
Signature · 1 line
2.22.0
author maintainer
#14 lore raw

PATCH v3 12/22 PM / devfreq: tegra30: Inline all one-line functions

In reply to Dmitry Osipenko

Depending on a kernel's configuration, a single line functions may not be inlined by compiler (like enabled ftracing for example). Let's inline such functions explicitly for consistency.

---
 drivers/devfreq/tegra30-devfreq.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
drivers/devfreq/tegra30-devfreq.c +7 -6
index 47a47be276ee..ecbd58504cd8 100644
@@ -181,28 +181,29 @@ static struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
 	{  250000,    100000 },
 };
 
-static u32 actmon_readl(struct tegra_devfreq *tegra, u32 offset)
+static inline u32 actmon_readl(struct tegra_devfreq *tegra, u32 offset)
 {
 	return readl_relaxed(tegra->regs + offset);
 }
 
-static void actmon_writel(struct tegra_devfreq *tegra, u32 val, u32 offset)
+static inline void actmon_writel(struct tegra_devfreq *tegra,
+				 u32 val, u32 offset)
 {
 	writel_relaxed(val, tegra->regs + offset);
 }
 
-static u32 device_readl(struct tegra_devfreq_device *dev, u32 offset)
+static inline u32 device_readl(struct tegra_devfreq_device *dev, u32 offset)
 {
 	return readl_relaxed(dev->regs + offset);
 }
 
-static void device_writel(struct tegra_devfreq_device *dev, u32 val,
-			  u32 offset)
+static inline void device_writel(struct tegra_devfreq_device *dev,
+				 u32 val, u32 offset)
 {
 	writel_relaxed(val, dev->regs + offset);
 }
 
-static unsigned long do_percent(unsigned long val, unsigned int pct)
+static inline unsigned long do_percent(unsigned long val, unsigned int pct)
 {
 	return val * pct / 100;
 }
Signature · 1 line
2.22.0
author maintainer
#15 lore raw

PATCH v3 13/22 PM / devfreq: tegra30: Constify structs

In reply to Dmitry Osipenko

Constify unmodifiable structs for consistency.

---
 drivers/devfreq/tegra30-devfreq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
drivers/devfreq/tegra30-devfreq.c +3 -3
index ecbd58504cd8..d3e117d827d2 100644
@@ -106,7 +106,7 @@ enum tegra_actmon_device {
 	MCCPU,
 };
 
-static struct tegra_devfreq_device_config actmon_device_configs[] = {
+static const struct tegra_devfreq_device_config actmon_device_configs[] = {
 	{
 		/* MCALL: All memory accesses (including from the CPUs) */
 		.offset = 0x1c0,
@@ -171,7 +171,7 @@ struct tegra_actmon_emc_ratio {
 	unsigned long emc_freq;
 };
 
-static struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
+static const struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
 	{ 1400000, ULONG_MAX },
 	{ 1200000,    750000 },
 	{ 1100000,    600000 },
@@ -210,7 +210,7 @@ static inline unsigned long do_percent(unsigned long val, unsigned int pct)
 
 static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra)
 {
-	struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
+	const struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
 	unsigned int cpu_freq = cpufreq_get(0);
 	unsigned int i;
 
Signature · 1 line
2.22.0
author maintainer
#16 lore raw

PATCH v3 14/22 PM / devfreq: tegra30: Ensure that target freq won't overflow

In reply to Dmitry Osipenko

Potentially very high boosting could cause an integer overflow for a highly clocked memory after conversion to MHz.

---
 drivers/devfreq/tegra30-devfreq.c | 1 +
 1 file changed, 1 insertion(+)
drivers/devfreq/tegra30-devfreq.c +1 -0
index d3e117d827d2..f86593ab3008 100644
@@ -459,6 +459,7 @@ static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
 {	unsigned long target_freq;
 
 	target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq;
+	target_freq = min(target_freq, ULONG_MAX / KHZ);
 	target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);
 
 	return target_freq;
Signature · 1 line
2.22.0
author maintainer
#17 lore raw

PATCH v3 15/22 PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out

In reply to Dmitry Osipenko

There is another kHz-conversion bug in the code, resulting in integer overflow. Although, this time the resulting value is 4294966296 and it's close to ULONG_MAX, which is okay in this case.

---
 drivers/devfreq/tegra30-devfreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/devfreq/tegra30-devfreq.c +1 -1
index f86593ab3008..9a6ede689991 100644
@@ -172,7 +172,7 @@ struct tegra_actmon_emc_ratio {
 };
 
 static const struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
-	{ 1400000, ULONG_MAX },
+	{ 1400000, ULONG_MAX / KHZ },
 	{ 1200000,    750000 },
 	{ 1100000,    600000 },
 	{ 1000000,    500000 },
Signature · 1 line
2.22.0
author maintainer
#18 lore raw

PATCH v3 16/22 PM / devfreq: tegra30: Use kHz units uniformly in the code

In reply to Dmitry Osipenko

Now that all kHz-conversion related bugs are fixed, we can use the kHz uniformly. This makes code cleaner and avoids integer divisions in the code, which is useful in a case of Tegra30 that has Cortex A9 CPU that doesn't support integer division instructions, hence all divisions are actually made in software mode. Another small benefit from this change is that now powertop utility correctly displays devfreq's stats, for some reason it expects them to be in kHz.

---
 drivers/devfreq/tegra30-devfreq.c | 78 +++++++++++++++++--------------
 1 file changed, 43 insertions(+), 35 deletions(-)
drivers/devfreq/tegra30-devfreq.c +43 -35
index 9a6ede689991..61d9601766fc 100644
@@ -72,6 +72,8 @@
 
 #define KHZ							1000
 
+#define KHZ_MAX						(ULONG_MAX / KHZ)
+
 /* Assume that the bus is saturated if the utilization is 25% */
 #define BUS_SATURATION_RATIO					25
 
@@ -124,7 +126,7 @@ 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 = 50000 / ACTMON_SAMPLING_PERIOD,
 	},
 };
 
@@ -137,8 +139,11 @@ struct tegra_devfreq_device {
 	const struct tegra_devfreq_device_config *config;
 	void __iomem *regs;
 
-	/* Average event count sampled in the last interrupt */
-	u32 avg_count;
+	/*
+	 * Average event count sampled in the last interrupt and converted
+	 * to frequency value.
+	 */
+	u32 avg_freq;
 
 	/*
 	 * Extra frequency to increase the target by due to consecutive
@@ -172,7 +177,7 @@ struct tegra_actmon_emc_ratio {
 };
 
 static const struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
-	{ 1400000, ULONG_MAX / KHZ },
+	{ 1400000,    KHZ_MAX },
 	{ 1200000,    750000 },
 	{ 1100000,    600000 },
 	{ 1000000,    500000 },
@@ -234,7 +239,7 @@ tegra_actmon_account_cpu_freq(struct tegra_devfreq *tegra,
 	unsigned long static_cpu_emc_freq;
 
 	if (dev->config->avg_dependency_threshold &&
-	    dev->config->avg_dependency_threshold < dev->avg_count) {
+	    dev->config->avg_dependency_threshold < dev->avg_freq) {
 		static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra);
 		target_freq = max(target_freq, static_cpu_emc_freq);
 	}
@@ -265,7 +270,7 @@ static unsigned long tegra_actmon_upper_freq(struct tegra_devfreq *tegra,
 
 	opp = dev_pm_opp_find_freq_ceil(tegra->devfreq->dev.parent, &upper);
 	if (IS_ERR(opp))
-		upper = ULONG_MAX;
+		upper = KHZ_MAX;
 	else
 		dev_pm_opp_put(opp);
 
@@ -287,7 +292,7 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 	 * range in a case where target_freq falls into a range of
 	 * next_possible_opp_freq - 1MHz.
 	 */
-	target_freq = round_down(target_freq, 1000000);
+	target_freq = round_down(target_freq, 1000);
 
 	/* watermarks are set at the borders of the corresponding OPPs */
 	*lower = tegra_actmon_lower_freq(tegra, target_freq);
@@ -296,9 +301,6 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 	dev_dbg(ddev, "%03x: target_freq %lu lower freq %lu upper freq %lu\n",
 		offset, target_freq, *lower, *upper);
 
-	*lower /= KHZ;
-	*upper /= KHZ;
-
 	/*
 	 * The upper watermark should take into account CPU's frequency
 	 * because cpu_to_emc_rate() may override the target_freq with
@@ -314,22 +316,23 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
 					   struct tegra_devfreq_device *dev)
 {
-	unsigned long lower, upper, freq;
+	unsigned long avg_threshold, lower, upper;
 
-	freq = dev->avg_count / ACTMON_SAMPLING_PERIOD * KHZ;
-	tegra_actmon_get_lower_upper(tegra, dev, freq, &lower, &upper);
+	tegra_actmon_get_lower_upper(tegra, dev, dev->avg_freq, &lower, &upper);
+
+	avg_threshold = dev->config->avg_dependency_threshold;
+	avg_threshold = avg_threshold * ACTMON_SAMPLING_PERIOD;
 
 	/*
 	 * We want to get interrupts when MCCPU client crosses the
 	 * dependency threshold in order to take into / out of account
 	 * the CPU's freq.
 	 */
-	if (lower < dev->config->avg_dependency_threshold &&
-	    upper > dev->config->avg_dependency_threshold) {
-		if (dev->avg_count < dev->config->avg_dependency_threshold)
-			upper = dev->config->avg_dependency_threshold;
+	if (lower < avg_threshold && upper > avg_threshold) {
+		if (dev->avg_freq < dev->config->avg_dependency_threshold)
+			upper = avg_threshold;
 		else
-			lower = dev->config->avg_dependency_threshold;
+			lower = avg_threshold;
 	}
 
 	device_writel(dev, lower, ACTMON_DEV_AVG_LOWER_WMARK);
@@ -368,8 +371,7 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 	 * device. Once that mark is hit and boosting is stopped, the
 	 * interrupt is disabled by ISR.
 	 */
-	freq = dev->avg_count / ACTMON_SAMPLING_PERIOD * KHZ;
-	tegra_actmon_get_lower_upper(tegra, dev, freq, &lower, &upper);
+	tegra_actmon_get_lower_upper(tegra, dev, dev->avg_freq, &lower, &upper);
 
 	delta = do_percent(upper - lower, dev->config->boost_down_threshold);
 	device_writel(dev, lower + delta, ACTMON_DEV_LOWER_WMARK);
@@ -396,14 +398,16 @@ static void actmon_device_debug(struct tegra_devfreq *tegra,
 static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
-	u32 intr_status, dev_ctrl, avg_intr_mask;
+	u32 intr_status, dev_ctrl, avg_intr_mask, avg_count;
 
 	actmon_device_debug(tegra, dev, "isr+");
 
-	dev->avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
 	intr_status = device_readl(dev, ACTMON_DEV_INTR_STATUS);
+	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;
+
 	avg_intr_mask = ACTMON_DEV_INTR_AVG_BELOW_WMARK |
 			ACTMON_DEV_INTR_AVG_ABOVE_WMARK;
 
@@ -458,8 +462,7 @@ static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
 					  struct tegra_devfreq_device *dev)
 {	unsigned long target_freq;
 
-	target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq;
-	target_freq = min(target_freq, ULONG_MAX / KHZ);
+	target_freq = min(dev->avg_freq + dev->boost_freq, KHZ_MAX);
 	target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);
 
 	return target_freq;
@@ -496,6 +499,7 @@ static int tegra_actmon_clk_notify_cb(struct notifier_block *nb,
 	struct clk_notifier_data *data = ptr;
 	struct tegra_devfreq_device *dev;
 	struct tegra_devfreq *tegra;
+	unsigned long freq;
 	unsigned int i;
 
 	if (action != POST_RATE_CHANGE)
@@ -503,6 +507,8 @@ static int tegra_actmon_clk_notify_cb(struct notifier_block *nb,
 
 	tegra = container_of(nb, struct tegra_devfreq, clk_rate_change_nb);
 
+	freq = data->new_rate / KHZ;
+
 	/*
 	 * EMC rate could change due to three reasons:
 	 *
@@ -524,7 +530,7 @@ static int tegra_actmon_clk_notify_cb(struct notifier_block *nb,
 		dev = &tegra->devices[i];
 
 		tegra_devfreq_update_avg_wmark(tegra, dev);
-		tegra_devfreq_update_wmark(tegra, dev, data->new_rate);
+		tegra_devfreq_update_wmark(tegra, dev, freq);
 	}
 
 	return NOTIFY_OK;
@@ -564,17 +570,17 @@ static int tegra_actmon_cpu_notify_cb(struct notifier_block *nb,
 static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 					  struct tegra_devfreq_device *dev)
 {
-	u32 val = 0, target_freq;
+	u32 val = 0;
 
 	/* we don't want boosting on restart */
 	dev->boost_freq = 0;
 
-	target_freq = clk_get_rate(tegra->emc_clock) / KHZ;
-	dev->avg_count = target_freq * ACTMON_SAMPLING_PERIOD;
-	device_writel(dev, dev->avg_count, ACTMON_DEV_INIT_AVG);
+	dev->avg_freq = clk_get_rate(tegra->emc_clock) / KHZ;
+	device_writel(dev, dev->avg_freq * ACTMON_SAMPLING_PERIOD,
+		      ACTMON_DEV_INIT_AVG);
 
 	tegra_devfreq_update_avg_wmark(tegra, dev);
-	tegra_devfreq_update_wmark(tegra, dev, target_freq);
+	tegra_devfreq_update_wmark(tegra, dev, dev->avg_freq);
 
 	device_writel(dev, ACTMON_COUNT_WEIGHT, ACTMON_DEV_COUNT_WEIGHT);
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
@@ -686,7 +692,7 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
 	rate = dev_pm_opp_get_freq(opp);
 	dev_pm_opp_put(opp);
 
-	err = clk_set_min_rate(tegra->emc_clock, rate);
+	err = clk_set_min_rate(tegra->emc_clock, rate * KHZ);
 	if (err)
 		return err;
 
@@ -709,7 +715,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
 	struct tegra_devfreq_device *actmon_dev;
 	unsigned long cur_freq;
 
-	cur_freq = clk_get_rate(tegra->emc_clock);
+	cur_freq = clk_get_rate(tegra->emc_clock) / KHZ;
 
 	/* To be used by the tegra governor */
 	stat->private_data = tegra;
@@ -726,7 +732,7 @@ 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 / KHZ * ACTMON_SAMPLING_PERIOD;
+	stat->total_time = cur_freq * ACTMON_SAMPLING_PERIOD;
 
 	stat->busy_time = min(stat->busy_time, stat->total_time);
 
@@ -772,7 +778,7 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
 		actmon_device_debug(tegra, dev, "upd");
 	}
 
-	*freq = target_freq * KHZ;
+	*freq = target_freq;
 
 	return 0;
 }
@@ -908,7 +914,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 			goto remove_opps;
 		}
 
-		err = dev_pm_opp_add(&pdev->dev, rate, 0);
+		err = dev_pm_opp_add(&pdev->dev, rate / KHZ, 0);
 		if (err) {
 			dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
 			goto remove_opps;
@@ -928,6 +934,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	}
 
 	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
+	tegra_devfreq_profile.initial_freq /= KHZ;
+
 	devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile,
 				     "tegra_actmon", NULL);
 	if (IS_ERR(tegra->devfreq)) {
Signature · 1 line
2.22.0
author maintainer
#19 lore raw

PATCH v3 17/22 PM / devfreq: tegra30: Use tracepoints for debugging

In reply to Dmitry Osipenko

Debug messages create too much CPU and memory activity by themselves, so it's difficult to debug lower rates and catch unwanted interrupts that happen rarely. Tracepoints are ideal in that regards because they do not contribute to the sampled date at all. This allowed me to catch few problems which are fixed by the followup patches, without tracepoints it would be much harder to do.

---
 drivers/devfreq/tegra30-devfreq.c      |  43 +++-------
 include/trace/events/tegra30_devfreq.h | 105 +++++++++++++++++++++++++
 2 files changed, 117 insertions(+), 31 deletions(-)
 create mode 100644 include/trace/events/tegra30_devfreq.h
drivers/devfreq/tegra30-devfreq.c +12 -31
index 61d9601766fc..c1ab7af07daa 100644
@@ -19,6 +19,9 @@
 #include <linux/reset.h>
 #include <linux/workqueue.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/tegra30_devfreq.h>
+
 #include "governor.h"
 
 #define ACTMON_GLB_STATUS					0x0
@@ -283,9 +286,6 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 					 unsigned long *lower,
 					 unsigned long *upper)
 {
-	struct device *ddev = tegra->devfreq->dev.parent;
-	u32 offset = dev->config->offset;
-
 	/*
 	 * Memory frequencies are guaranteed to have 1MHz granularity
 	 * and thus we need this rounding down to get a proper watermarks
@@ -298,8 +298,8 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 	*lower = tegra_actmon_lower_freq(tegra, target_freq);
 	*upper = tegra_actmon_upper_freq(tegra, target_freq);
 
-	dev_dbg(ddev, "%03x: target_freq %lu lower freq %lu upper freq %lu\n",
-		offset, target_freq, *lower, *upper);
+	trace_device_lower_upper(dev->config->offset, target_freq,
+				 *lower, *upper);
 
 	/*
 	 * The upper watermark should take into account CPU's frequency
@@ -377,30 +377,13 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 	device_writel(dev, lower + delta, ACTMON_DEV_LOWER_WMARK);
 }
 
-static void actmon_device_debug(struct tegra_devfreq *tegra,
-				struct tegra_devfreq_device *dev,
-				const char *prefix)
-{
-	dev_dbg(tegra->devfreq->dev.parent,
-		"%03x: %s: 0x%08x 0x%08x a %u %u %u c %u %u %u b %lu cpu %u\n",
-		dev->config->offset, prefix,
-		device_readl(dev, ACTMON_DEV_INTR_STATUS),
-		device_readl(dev, ACTMON_DEV_CTRL),
-		device_readl(dev, ACTMON_DEV_AVG_COUNT),
-		device_readl(dev, ACTMON_DEV_AVG_LOWER_WMARK),
-		device_readl(dev, ACTMON_DEV_AVG_UPPER_WMARK),
-		device_readl(dev, ACTMON_DEV_COUNT),
-		device_readl(dev, ACTMON_DEV_LOWER_WMARK),
-		device_readl(dev, ACTMON_DEV_UPPER_WMARK),
-		dev->boost_freq, cpufreq_get(0));
-}
-
 static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
 	u32 intr_status, dev_ctrl, avg_intr_mask, avg_count;
 
-	actmon_device_debug(tegra, dev, "isr+");
+	trace_device_isr_enter(tegra->regs, dev->config->offset,
+			       dev->boost_freq, cpufreq_get(0));
 
 	intr_status = device_readl(dev, ACTMON_DEV_INTR_STATUS);
 	avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
@@ -455,7 +438,8 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 	device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
 
-	actmon_device_debug(tegra, dev, "isr-");
+	trace_device_isr_exit(tegra->regs, dev->config->offset,
+			      dev->boost_freq, cpufreq_get(0));
 }
 
 static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
@@ -748,7 +732,6 @@ static struct devfreq_dev_profile tegra_devfreq_profile = {
 static int tegra_governor_get_target(struct devfreq *devfreq,
 				     unsigned long *freq)
 {
-	struct device *ddev = devfreq->dev.parent;
 	struct devfreq_dev_status *stat;
 	struct tegra_devfreq *tegra;
 	struct tegra_devfreq_device *dev;
@@ -769,13 +752,11 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
 		dev = &tegra->devices[i];
 
 		dev_target_freq = actmon_update_target(tegra, dev);
-
 		target_freq = max(target_freq, dev_target_freq);
 
-		dev_dbg(ddev, "%03x: upd: dev_target_freq %lu\n",
-			dev->config->offset, dev_target_freq);
-
-		actmon_device_debug(tegra, dev, "upd");
+		trace_device_target_freq(dev->config->offset, dev_target_freq);
+		trace_device_target_update(tegra->regs, dev->config->offset,
+					   dev->boost_freq, cpufreq_get(0));
 	}
 
 	*freq = target_freq;
include/trace/events/tegra30_devfreq.h new file +105 -0

105 lines not on this page · raw message

Signature · 1 line
2.22.0
author maintainer
#20 lore raw

PATCH v3 18/22 PM / devfreq: tegra30: Optimize CPUFreq notifier

In reply to Dmitry Osipenko

When CPU's memory activity is low or memory activity is high such that CPU's frequency contribution to the boosting is not taken into account, then there is no need to schedule devfreq's update. This eliminates unnecessary CPU activity during of idling caused by the scheduled work.

---
 drivers/devfreq/tegra30-devfreq.c | 73 +++++++++++++++++++++++++++----
 1 file changed, 64 insertions(+), 9 deletions(-)
drivers/devfreq/tegra30-devfreq.c +64 -9
index c1ab7af07daa..e8f7cc56a340 100644
@@ -216,10 +216,10 @@ static inline unsigned long do_percent(unsigned long val, unsigned int pct)
 	return val * pct / 100;
 }
 
-static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra)
+static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
+					    unsigned int cpu_freq)
 {
 	const struct tegra_actmon_emc_ratio *ratio = actmon_emc_ratios;
-	unsigned int cpu_freq = cpufreq_get(0);
 	unsigned int i;
 
 	for (i = 0; i < ARRAY_SIZE(actmon_emc_ratios); i++, ratio++) {
@@ -239,15 +239,15 @@ tegra_actmon_account_cpu_freq(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev,
 			      unsigned long target_freq)
 {
-	unsigned long static_cpu_emc_freq;
+	unsigned long cpu_emc_freq = 0;
 
-	if (dev->config->avg_dependency_threshold &&
-	    dev->config->avg_dependency_threshold < dev->avg_freq) {
-		static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra);
-		target_freq = max(target_freq, static_cpu_emc_freq);
-	}
+	if (!dev->config->avg_dependency_threshold)
+		return target_freq;
 
-	return target_freq;
+	if (dev->avg_freq > dev->config->avg_dependency_threshold)
+		cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpufreq_get(0));
+
+	return max(target_freq, cpu_emc_freq);
 }
 
 static unsigned long tegra_actmon_lower_freq(struct tegra_devfreq *tegra,
@@ -530,16 +530,71 @@ static void tegra_actmon_delayed_update(struct work_struct *work)
 	mutex_unlock(&tegra->devfreq->lock);
 }
 
+static unsigned long
+tegra_actmon_cpufreq_contribution(struct tegra_devfreq *tegra,
+				  unsigned int cpu_freq)
+{
+	unsigned long freq, static_cpu_emc_freq;
+
+	/* check whether CPU's freq is taken into account at all */
+	if (tegra->devices[MCCPU].avg_freq <=
+	    tegra->devices[MCCPU].config->avg_dependency_threshold)
+		return 0;
+
+	static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
+
+	/* compare static CPU-EMC freq with MCALL */
+	freq = tegra->devices[MCALL].avg_freq +
+	       tegra->devices[MCALL].boost_freq;
+
+	freq = tegra_actmon_upper_freq(tegra, freq);
+
+	if (freq == tegra->max_freq || freq >= static_cpu_emc_freq)
+		return 0;
+
+	/* compare static CPU-EMC freq with MCCPU */
+	freq = tegra->devices[MCCPU].avg_freq +
+	       tegra->devices[MCCPU].boost_freq;
+
+	freq = tegra_actmon_upper_freq(tegra, freq);
+
+	if (freq == tegra->max_freq || freq >= static_cpu_emc_freq)
+		return 0;
+
+	return static_cpu_emc_freq;
+}
+
 static int tegra_actmon_cpu_notify_cb(struct notifier_block *nb,
 				      unsigned long action, void *ptr)
 {
+	struct cpufreq_freqs *freqs = ptr;
 	struct tegra_devfreq *tegra;
+	unsigned long old, new;
 
 	if (action != CPUFREQ_POSTCHANGE)
 		return NOTIFY_OK;
 
 	tegra = container_of(nb, struct tegra_devfreq, cpu_rate_change_nb);
 
+	/*
+	 * Quickly check whether CPU frequency should be taken into account
+	 * at all, without blocking CPUFreq's core.
+	 */
+	if (mutex_trylock(&tegra->devfreq->lock)) {
+		old = tegra_actmon_cpufreq_contribution(tegra, freqs->old);
+		new = tegra_actmon_cpufreq_contribution(tegra, freqs->new);
+		mutex_unlock(&tegra->devfreq->lock);
+
+		/*
+		 * If CPU's frequency shouldn't be taken into account at
+		 * the moment, then there is no need to update the devfreq's
+		 * state because ISR will re-check CPU's frequency on the
+		 * next interrupt.
+		 */
+		if (old == new)
+			return NOTIFY_OK;
+	}
+
 	/*
 	 * CPUFreq driver should support CPUFREQ_ASYNC_NOTIFICATION in order
 	 * to allow asynchronous notifications. This means we can't block
Signature · 1 line
2.22.0
author maintainer
#21 lore raw

PATCH v3 19/22 PM / devfreq: tegra30: Optimize upper consecutive watermark selection

In reply to Dmitry Osipenko

The memory activity counter may get a bit higher than a watermark which is selected based on OPP that corresponds to a highest EMC rate, in this case watermark is lower than the actual memory activity is and thus results in unwanted "upper" interrupts.

---
 drivers/devfreq/tegra30-devfreq.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
drivers/devfreq/tegra30-devfreq.c +12 -1
index e8f7cc56a340..1105104445a9 100644
@@ -363,7 +363,18 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 	tegra_actmon_get_lower_upper(tegra, dev, freq - 1, &lower, &upper);
 
 	delta = do_percent(upper - lower, dev->config->boost_up_threshold);
-	device_writel(dev, lower + delta, ACTMON_DEV_UPPER_WMARK);
+
+	/*
+	 * The memory events count could go a bit higher than the maximum
+	 * defined by the OPPs, hence make the upper watermark infinitely
+	 * high to avoid unnecessary upper interrupts in that case.
+	 */
+	if (freq == tegra->max_freq)
+		upper = ULONG_MAX;
+	else
+		upper = lower + delta;
+
+	device_writel(dev, upper, ACTMON_DEV_UPPER_WMARK);
 
 	/*
 	 * Meanwhile the lower mark is based on the average value
Signature · 1 line
2.22.0
author maintainer
#22 lore raw

PATCH v3 20/22 PM / devfreq: tegra30: Optimize upper average watermark selection

In reply to Dmitry Osipenko

I noticed that CPU may be crossing the dependency threshold very frequently for some workloads and this results in a lot of interrupts which could be avoided if MCALL client is keeping actual EMC frequency at a higher rate.

---
 drivers/devfreq/tegra30-devfreq.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)
drivers/devfreq/tegra30-devfreq.c +18 -5
index 1105104445a9..5b1feaf8c16e 100644
@@ -314,7 +314,8 @@ static void tegra_actmon_get_lower_upper(struct tegra_devfreq *tegra,
 }
 
 static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
-					   struct tegra_devfreq_device *dev)
+					   struct tegra_devfreq_device *dev,
+					   unsigned long freq)
 {
 	unsigned long avg_threshold, lower, upper;
 
@@ -323,6 +324,15 @@ static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
 	avg_threshold = dev->config->avg_dependency_threshold;
 	avg_threshold = avg_threshold * ACTMON_SAMPLING_PERIOD;
 
+	/*
+	 * If cumulative EMC frequency selection is higher than the
+	 * device's, then there is no need to set upper watermark to
+	 * a lower value because it will result in unnecessary upper
+	 * interrupts.
+	 */
+	if (freq * ACTMON_SAMPLING_PERIOD > upper)
+		upper = freq * ACTMON_SAMPLING_PERIOD;
+
 	/*
 	 * We want to get interrupts when MCCPU client crosses the
 	 * dependency threshold in order to take into / out of account
@@ -392,6 +402,7 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
 	u32 intr_status, dev_ctrl, avg_intr_mask, avg_count;
+	unsigned long freq;
 
 	trace_device_isr_enter(tegra->regs, dev->config->offset,
 			       dev->boost_freq, cpufreq_get(0));
@@ -405,8 +416,10 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 	avg_intr_mask = ACTMON_DEV_INTR_AVG_BELOW_WMARK |
 			ACTMON_DEV_INTR_AVG_ABOVE_WMARK;
 
-	if (intr_status & avg_intr_mask)
-		tegra_devfreq_update_avg_wmark(tegra, dev);
+	if (intr_status & avg_intr_mask) {
+		freq = clk_get_rate(tegra->emc_clock) / KHZ;
+		tegra_devfreq_update_avg_wmark(tegra, dev, freq);
+	}
 
 	if (intr_status & ACTMON_DEV_INTR_CONSECUTIVE_UPPER) {
 		/*
@@ -524,7 +537,7 @@ static int tegra_actmon_clk_notify_cb(struct notifier_block *nb,
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
 		dev = &tegra->devices[i];
 
-		tegra_devfreq_update_avg_wmark(tegra, dev);
+		tegra_devfreq_update_avg_wmark(tegra, dev, freq);
 		tegra_devfreq_update_wmark(tegra, dev, freq);
 	}
 
@@ -629,7 +642,7 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 	device_writel(dev, dev->avg_freq * ACTMON_SAMPLING_PERIOD,
 		      ACTMON_DEV_INIT_AVG);
 
-	tegra_devfreq_update_avg_wmark(tegra, dev);
+	tegra_devfreq_update_avg_wmark(tegra, dev, dev->avg_freq);
 	tegra_devfreq_update_wmark(tegra, dev, dev->avg_freq);
 
 	device_writel(dev, ACTMON_COUNT_WEIGHT, ACTMON_DEV_COUNT_WEIGHT);
Signature · 1 line
2.22.0
author maintainer
#23 lore raw

PATCH v3 21/22 PM / devfreq: tegra30: Include appropriate header

In reply to Dmitry Osipenko

It's not very correct to include mod_devicetable.h for the OF device drivers and of_device.h should be included instead.

---
 drivers/devfreq/tegra30-devfreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/devfreq/tegra30-devfreq.c +1 -1
index 5b1feaf8c16e..3ca227c95829 100644
@@ -13,7 +13,7 @@
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/module.h>
-#include <linux/mod_devicetable.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/reset.h>
Signature · 1 line
2.22.0
author maintainer
#24 lore raw

PATCH v3 22/22 PM / devfreq: tegra20/30: Add Dmitry as a maintainer

In reply to Dmitry Osipenko

I was contributing to the NVIDIA Tegra20+ devfreq drivers recently and want to help keep them working and evolving in the future.

---
 MAINTAINERS | 9 +++++++++
 1 file changed, 9 insertions(+)
MAINTAINERS +9 -0
index 792d2d927712..bfd827417a27 100644
@@ -10250,6 +10250,15 @@ F:	include/linux/memblock.h
 F:	mm/memblock.c
 F:	Documentation/core-api/boot-time-mm.rst
 
+MEMORY FREQUENCY SCALING DRIVERS FOR NVIDIA TEGRA
+M:	Dmitry Osipenko <[email protected]>
+L:	[email protected]
+L:	[email protected]
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mzx/devfreq.git
+S:	Maintained
+F:	drivers/devfreq/tegra20-devfreq.c
+F:	drivers/devfreq/tegra30-devfreq.c
+
 MEMORY MANAGEMENT
 L:	[email protected]
 W:	http://www.linux-mm.org
Signature · 1 line
2.22.0