[PATCH 1/3] drm/msm: remove explicit devfreq status reset

[PATCH 1/3] drm/msm: remove explicit devfreq status reset

[Chia-I Wu]

It is redundant since commit 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS
constraints") because dev_pm_qos_update_request triggers get_dev_status.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 12641616acd3..317a95d42922 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -224,7 +224,6 @@ void msm_devfreq_boost(struct msm_gpu *gpu, unsigned factor)
 void msm_devfreq_active(struct msm_gpu *gpu)
 {
 	struct msm_gpu_devfreq *df = &gpu->devfreq;
-	struct devfreq_dev_status status;
 	unsigned int idle_time;
 
 	if (!has_devfreq(gpu))
@@ -248,12 +247,6 @@ void msm_devfreq_active(struct msm_gpu *gpu)
 
 	dev_pm_qos_update_request(&df->idle_freq,
 				  PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
-
-	/*
-	 * Reset the polling interval so we aren't inconsistent
-	 * about freq vs busy/total cycles
-	 */
-	msm_devfreq_get_dev_status(&gpu->pdev->dev, &status);
 }
 
 
-- 
2.36.0.rc0.470.gd361397f0d-goog

[PATCH 1/3] drm/msm: remove explicit devfreq status reset

[Chia-I Wu]

It is redundant since commit 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS
constraints") because dev_pm_qos_update_request triggers get_dev_status.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 12641616acd3..317a95d42922 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -224,7 +224,6 @@ void msm_devfreq_boost(struct msm_gpu *gpu, unsigned factor)
 void msm_devfreq_active(struct msm_gpu *gpu)
 {
 	struct msm_gpu_devfreq *df = &gpu->devfreq;
-	struct devfreq_dev_status status;
 	unsigned int idle_time;
 
 	if (!has_devfreq(gpu))
@@ -248,12 +247,6 @@ void msm_devfreq_active(struct msm_gpu *gpu)
 
 	dev_pm_qos_update_request(&df->idle_freq,
 				  PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
-
-	/*
-	 * Reset the polling interval so we aren't inconsistent
-	 * about freq vs busy/total cycles
-	 */
-	msm_devfreq_get_dev_status(&gpu->pdev->dev, &status);
 }
 
 
-- 
2.36.0.rc0.470.gd361397f0d-goog

[PATCH 2/3] drm/msm: simplify gpu_busy callback

[Chia-I Wu]

Move tracking and busy time calculation to msm_devfreq_get_dev_status.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 19 ++++++----------
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 15 +++++--------
 drivers/gpu/drm/msm/msm_gpu.h         |  9 +++-----
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 32 ++++++++++++++++++++++-----
 4 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
index 407f50a15faa..217615e0e850 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
@@ -1662,28 +1662,23 @@ static struct msm_ringbuffer *a5xx_active_ring(struct msm_gpu *gpu)
 	return a5xx_gpu->cur_ring;
 }
 
-static unsigned long a5xx_gpu_busy(struct msm_gpu *gpu)
+static u64 a5xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
 {
-	u64 busy_cycles, busy_time;
+	u64 busy_cycles;
 
 	/* Only read the gpu busy if the hardware is already active */
-	if (pm_runtime_get_if_in_use(&gpu->pdev->dev) == 0)
+	if (pm_runtime_get_if_in_use(&gpu->pdev->dev) == 0) {
+		*out_sample_rate = 1;
 		return 0;
+	}
 
 	busy_cycles = gpu_read64(gpu, REG_A5XX_RBBM_PERFCTR_RBBM_0_LO,
 			REG_A5XX_RBBM_PERFCTR_RBBM_0_HI);
-
-	busy_time = busy_cycles - gpu->devfreq.busy_cycles;
-	do_div(busy_time, clk_get_rate(gpu->core_clk) / 1000000);
-
-	gpu->devfreq.busy_cycles = busy_cycles;
+	*out_sample_rate = clk_get_rate(gpu->core_clk);
 
 	pm_runtime_put(&gpu->pdev->dev);
 
-	if (WARN_ON(busy_time > ~0LU))
-		return ~0LU;
-
-	return (unsigned long)busy_time;
+	return busy_cycles;
 }
 
 static uint32_t a5xx_get_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index ccc4fcf7a630..fba6259395dd 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1649,12 +1649,14 @@ static void a6xx_destroy(struct msm_gpu *gpu)
 	kfree(a6xx_gpu);
 }
 
-static unsigned long a6xx_gpu_busy(struct msm_gpu *gpu)
+static u64 a6xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
-	u64 busy_cycles, busy_time;
+	u64 busy_cycles;
 
+	/* 19.2MHz */
+	*out_sample_rate = 19200000;
 
 	/* Only read the gpu busy if the hardware is already active */
 	if (pm_runtime_get_if_in_use(a6xx_gpu->gmu.dev) == 0)
@@ -1664,17 +1666,10 @@ static unsigned long a6xx_gpu_busy(struct msm_gpu *gpu)
 			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_L,
 			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_H);
 
-	busy_time = (busy_cycles - gpu->devfreq.busy_cycles) * 10;
-	do_div(busy_time, 192);
-
-	gpu->devfreq.busy_cycles = busy_cycles;
 
 	pm_runtime_put(a6xx_gpu->gmu.dev);
 
-	if (WARN_ON(busy_time > ~0LU))
-		return ~0LU;
-
-	return (unsigned long)busy_time;
+	return busy_cycles;
 }
 
 static void a6xx_gpu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 02419f2ca2bc..389c6dab751b 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -62,7 +62,7 @@ struct msm_gpu_funcs {
 	/* for generation specific debugfs: */
 	void (*debugfs_init)(struct msm_gpu *gpu, struct drm_minor *minor);
 #endif
-	unsigned long (*gpu_busy)(struct msm_gpu *gpu);
+	u64 (*gpu_busy)(struct msm_gpu *gpu, unsigned long *out_sample_rate);
 	struct msm_gpu_state *(*gpu_state_get)(struct msm_gpu *gpu);
 	int (*gpu_state_put)(struct msm_gpu_state *state);
 	unsigned long (*gpu_get_freq)(struct msm_gpu *gpu);
@@ -106,11 +106,8 @@ struct msm_gpu_devfreq {
 	struct dev_pm_qos_request boost_freq;
 
 	/**
-	 * busy_cycles:
-	 *
-	 * Used by implementation of gpu->gpu_busy() to track the last
-	 * busy counter value, for calculating elapsed busy cycles since
-	 * last sampling period.
+	 * busy_cycles: Last busy counter value, for calculating elapsed busy
+	 * cycles since last sampling period.
 	 */
 	u64 busy_cycles;
 
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 317a95d42922..f531015107c3 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -49,18 +49,38 @@ static unsigned long get_freq(struct msm_gpu *gpu)
 	return clk_get_rate(gpu->core_clk);
 }
 
-static int msm_devfreq_get_dev_status(struct device *dev,
+static void get_raw_dev_status(struct msm_gpu *gpu,
 		struct devfreq_dev_status *status)
 {
-	struct msm_gpu *gpu = dev_to_gpu(dev);
+	struct msm_gpu_devfreq *df = &gpu->devfreq;
+	u64 busy_cycles, busy_time;
+	unsigned long sample_rate;
 	ktime_t time;
 
 	status->current_frequency = get_freq(gpu);
-	status->busy_time = gpu->funcs->gpu_busy(gpu);
-
+	busy_cycles = gpu->funcs->gpu_busy(gpu, &sample_rate);
 	time = ktime_get();
-	status->total_time = ktime_us_delta(time, gpu->devfreq.time);
-	gpu->devfreq.time = time;
+
+	busy_time = busy_cycles - df->busy_cycles;
+	status->total_time = ktime_us_delta(time, df->time);
+
+	df->busy_cycles = busy_cycles;
+	df->time = time;
+
+	busy_time *= USEC_PER_SEC;
+	do_div(busy_time, sample_rate);
+	if (WARN_ON(busy_time > ~0LU))
+		busy_time = ~0LU;
+
+	status->busy_time = busy_time;
+}
+
+static int msm_devfreq_get_dev_status(struct device *dev,
+		struct devfreq_dev_status *status)
+{
+	struct msm_gpu *gpu = dev_to_gpu(dev);
+
+	get_raw_dev_status(gpu, status);
 
 	return 0;
 }
-- 
2.36.0.rc0.470.gd361397f0d-goog

[PATCH 2/3] drm/msm: simplify gpu_busy callback

[Chia-I Wu]

Move tracking and busy time calculation to msm_devfreq_get_dev_status.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 19 ++++++----------
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 15 +++++--------
 drivers/gpu/drm/msm/msm_gpu.h         |  9 +++-----
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 32 ++++++++++++++++++++++-----
 4 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
index 407f50a15faa..217615e0e850 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
@@ -1662,28 +1662,23 @@ static struct msm_ringbuffer *a5xx_active_ring(struct msm_gpu *gpu)
 	return a5xx_gpu->cur_ring;
 }
 
-static unsigned long a5xx_gpu_busy(struct msm_gpu *gpu)
+static u64 a5xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
 {
-	u64 busy_cycles, busy_time;
+	u64 busy_cycles;
 
 	/* Only read the gpu busy if the hardware is already active */
-	if (pm_runtime_get_if_in_use(&gpu->pdev->dev) == 0)
+	if (pm_runtime_get_if_in_use(&gpu->pdev->dev) == 0) {
+		*out_sample_rate = 1;
 		return 0;
+	}
 
 	busy_cycles = gpu_read64(gpu, REG_A5XX_RBBM_PERFCTR_RBBM_0_LO,
 			REG_A5XX_RBBM_PERFCTR_RBBM_0_HI);
-
-	busy_time = busy_cycles - gpu->devfreq.busy_cycles;
-	do_div(busy_time, clk_get_rate(gpu->core_clk) / 1000000);
-
-	gpu->devfreq.busy_cycles = busy_cycles;
+	*out_sample_rate = clk_get_rate(gpu->core_clk);
 
 	pm_runtime_put(&gpu->pdev->dev);
 
-	if (WARN_ON(busy_time > ~0LU))
-		return ~0LU;
-
-	return (unsigned long)busy_time;
+	return busy_cycles;
 }
 
 static uint32_t a5xx_get_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index ccc4fcf7a630..fba6259395dd 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1649,12 +1649,14 @@ static void a6xx_destroy(struct msm_gpu *gpu)
 	kfree(a6xx_gpu);
 }
 
-static unsigned long a6xx_gpu_busy(struct msm_gpu *gpu)
+static u64 a6xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
-	u64 busy_cycles, busy_time;
+	u64 busy_cycles;
 
+	/* 19.2MHz */
+	*out_sample_rate = 19200000;
 
 	/* Only read the gpu busy if the hardware is already active */
 	if (pm_runtime_get_if_in_use(a6xx_gpu->gmu.dev) == 0)
@@ -1664,17 +1666,10 @@ static unsigned long a6xx_gpu_busy(struct msm_gpu *gpu)
 			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_L,
 			REG_A6XX_GMU_CX_GMU_POWER_COUNTER_XOCLK_0_H);
 
-	busy_time = (busy_cycles - gpu->devfreq.busy_cycles) * 10;
-	do_div(busy_time, 192);
-
-	gpu->devfreq.busy_cycles = busy_cycles;
 
 	pm_runtime_put(a6xx_gpu->gmu.dev);
 
-	if (WARN_ON(busy_time > ~0LU))
-		return ~0LU;
-
-	return (unsigned long)busy_time;
+	return busy_cycles;
 }
 
 static void a6xx_gpu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 02419f2ca2bc..389c6dab751b 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -62,7 +62,7 @@ struct msm_gpu_funcs {
 	/* for generation specific debugfs: */
 	void (*debugfs_init)(struct msm_gpu *gpu, struct drm_minor *minor);
 #endif
-	unsigned long (*gpu_busy)(struct msm_gpu *gpu);
+	u64 (*gpu_busy)(struct msm_gpu *gpu, unsigned long *out_sample_rate);
 	struct msm_gpu_state *(*gpu_state_get)(struct msm_gpu *gpu);
 	int (*gpu_state_put)(struct msm_gpu_state *state);
 	unsigned long (*gpu_get_freq)(struct msm_gpu *gpu);
@@ -106,11 +106,8 @@ struct msm_gpu_devfreq {
 	struct dev_pm_qos_request boost_freq;
 
 	/**
-	 * busy_cycles:
-	 *
-	 * Used by implementation of gpu->gpu_busy() to track the last
-	 * busy counter value, for calculating elapsed busy cycles since
-	 * last sampling period.
+	 * busy_cycles: Last busy counter value, for calculating elapsed busy
+	 * cycles since last sampling period.
 	 */
 	u64 busy_cycles;
 
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 317a95d42922..f531015107c3 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -49,18 +49,38 @@ static unsigned long get_freq(struct msm_gpu *gpu)
 	return clk_get_rate(gpu->core_clk);
 }
 
-static int msm_devfreq_get_dev_status(struct device *dev,
+static void get_raw_dev_status(struct msm_gpu *gpu,
 		struct devfreq_dev_status *status)
 {
-	struct msm_gpu *gpu = dev_to_gpu(dev);
+	struct msm_gpu_devfreq *df = &gpu->devfreq;
+	u64 busy_cycles, busy_time;
+	unsigned long sample_rate;
 	ktime_t time;
 
 	status->current_frequency = get_freq(gpu);
-	status->busy_time = gpu->funcs->gpu_busy(gpu);
-
+	busy_cycles = gpu->funcs->gpu_busy(gpu, &sample_rate);
 	time = ktime_get();
-	status->total_time = ktime_us_delta(time, gpu->devfreq.time);
-	gpu->devfreq.time = time;
+
+	busy_time = busy_cycles - df->busy_cycles;
+	status->total_time = ktime_us_delta(time, df->time);
+
+	df->busy_cycles = busy_cycles;
+	df->time = time;
+
+	busy_time *= USEC_PER_SEC;
+	do_div(busy_time, sample_rate);
+	if (WARN_ON(busy_time > ~0LU))
+		busy_time = ~0LU;
+
+	status->busy_time = busy_time;
+}
+
+static int msm_devfreq_get_dev_status(struct device *dev,
+		struct devfreq_dev_status *status)
+{
+	struct msm_gpu *gpu = dev_to_gpu(dev);
+
+	get_raw_dev_status(gpu, status);
 
 	return 0;
 }
-- 
2.36.0.rc0.470.gd361397f0d-goog

[PATCH 3/3] drm/msm: return the average load over the polling period

[Chia-I Wu]

simple_ondemand interacts poorly with clamp_to_idle.  It only looks at
the load since the last get_dev_status call, while it should really look
at the load over polling_ms.  When clamp_to_idle true, it almost always
picks the lowest frequency on active because the gpu is idle between
msm_devfreq_idle/msm_devfreq_active.

This logic could potentially be moved into devfreq core.

Fixes: 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS constraints")
Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu.h         |  3 ++
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 ++++++++++++++++++++++++++-
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 389c6dab751b..143c56f5185b 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -9,6 +9,7 @@
 
 #include <linux/adreno-smmu-priv.h>
 #include <linux/clk.h>
+#include <linux/devfreq.h>
 #include <linux/interconnect.h>
 #include <linux/pm_opp.h>
 #include <linux/regulator/consumer.h>
@@ -117,6 +118,8 @@ struct msm_gpu_devfreq {
 	/** idle_time: Time of last transition to idle: */
 	ktime_t idle_time;
 
+	struct devfreq_dev_status average_status;
+
 	/**
 	 * idle_work:
 	 *
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index f531015107c3..d2539ca78c29 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -9,6 +9,7 @@
 
 #include <linux/devfreq.h>
 #include <linux/devfreq_cooling.h>
+#include <linux/math64.h>
 #include <linux/units.h>
 
 /*
@@ -75,12 +76,69 @@ static void get_raw_dev_status(struct msm_gpu *gpu,
 	status->busy_time = busy_time;
 }
 
+static void update_average_dev_status(struct msm_gpu *gpu,
+		const struct devfreq_dev_status *raw)
+{
+	struct msm_gpu_devfreq *df = &gpu->devfreq;
+	const u32 polling_ms = df->devfreq->profile->polling_ms;
+	const u32 max_history_ms = polling_ms * 11 / 10;
+	struct devfreq_dev_status *avg = &df->average_status;
+	u64 avg_freq;
+
+	/* simple_ondemand governor interacts poorly with gpu->clamp_to_idle.
+	 * When we enforce the constraint on idle, it calls get_dev_status
+	 * which would normally reset the stats.  When we remove the
+	 * constraint on active, it calls get_dev_status again where busy_time
+	 * would be 0.
+	 *
+	 * To remedy this, we always return the average load over the past
+	 * polling_ms.
+	 */
+
+	/* raw is longer than polling_ms or avg has no history */
+	if (div_u64(raw->total_time, USEC_PER_MSEC) >= polling_ms ||
+	    !avg->total_time) {
+		*avg = *raw;
+		return;
+	}
+
+	/* Truncate the oldest history first.
+	 *
+	 * Because we keep the history with a single devfreq_dev_status,
+	 * rather than a list of devfreq_dev_status, we have to assume freq
+	 * and load are the same over avg->total_time.  We can scale down
+	 * avg->busy_time and avg->total_time by the same factor to drop
+	 * history.
+	 */
+	if (div_u64(avg->total_time + raw->total_time, USEC_PER_MSEC) >=
+			max_history_ms) {
+		const u32 new_total_time = polling_ms * USEC_PER_MSEC -
+			raw->total_time;
+		avg->busy_time = div_u64(
+				mul_u32_u32(avg->busy_time, new_total_time),
+				avg->total_time);
+		avg->total_time = new_total_time;
+	}
+
+	/* compute the average freq over avg->total_time + raw->total_time */
+	avg_freq = mul_u32_u32(avg->current_frequency, avg->total_time);
+	avg_freq += mul_u32_u32(raw->current_frequency, raw->total_time);
+	do_div(avg_freq, avg->total_time + raw->total_time);
+
+	avg->current_frequency = avg_freq;
+	avg->busy_time += raw->busy_time;
+	avg->total_time += raw->total_time;
+}
+
 static int msm_devfreq_get_dev_status(struct device *dev,
 		struct devfreq_dev_status *status)
 {
 	struct msm_gpu *gpu = dev_to_gpu(dev);
+	struct devfreq_dev_status raw;
 
-	get_raw_dev_status(gpu, status);
+	get_raw_dev_status(gpu, &raw);
+	update_average_dev_status(gpu, &raw);
+	*status = gpu->devfreq.average_status;
 
 	return 0;
 }
-- 
2.36.0.rc0.470.gd361397f0d-goog

[PATCH 3/3] drm/msm: return the average load over the polling period

[Chia-I Wu]

simple_ondemand interacts poorly with clamp_to_idle.  It only looks at
the load since the last get_dev_status call, while it should really look
at the load over polling_ms.  When clamp_to_idle true, it almost always
picks the lowest frequency on active because the gpu is idle between
msm_devfreq_idle/msm_devfreq_active.

This logic could potentially be moved into devfreq core.

Fixes: 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS constraints")
Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu.h         |  3 ++
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 ++++++++++++++++++++++++++-
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 389c6dab751b..143c56f5185b 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -9,6 +9,7 @@
 
 #include <linux/adreno-smmu-priv.h>
 #include <linux/clk.h>
+#include <linux/devfreq.h>
 #include <linux/interconnect.h>
 #include <linux/pm_opp.h>
 #include <linux/regulator/consumer.h>
@@ -117,6 +118,8 @@ struct msm_gpu_devfreq {
 	/** idle_time: Time of last transition to idle: */
 	ktime_t idle_time;
 
+	struct devfreq_dev_status average_status;
+
 	/**
 	 * idle_work:
 	 *
diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index f531015107c3..d2539ca78c29 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -9,6 +9,7 @@
 
 #include <linux/devfreq.h>
 #include <linux/devfreq_cooling.h>
+#include <linux/math64.h>
 #include <linux/units.h>
 
 /*
@@ -75,12 +76,69 @@ static void get_raw_dev_status(struct msm_gpu *gpu,
 	status->busy_time = busy_time;
 }
 
+static void update_average_dev_status(struct msm_gpu *gpu,
+		const struct devfreq_dev_status *raw)
+{
+	struct msm_gpu_devfreq *df = &gpu->devfreq;
+	const u32 polling_ms = df->devfreq->profile->polling_ms;
+	const u32 max_history_ms = polling_ms * 11 / 10;
+	struct devfreq_dev_status *avg = &df->average_status;
+	u64 avg_freq;
+
+	/* simple_ondemand governor interacts poorly with gpu->clamp_to_idle.
+	 * When we enforce the constraint on idle, it calls get_dev_status
+	 * which would normally reset the stats.  When we remove the
+	 * constraint on active, it calls get_dev_status again where busy_time
+	 * would be 0.
+	 *
+	 * To remedy this, we always return the average load over the past
+	 * polling_ms.
+	 */
+
+	/* raw is longer than polling_ms or avg has no history */
+	if (div_u64(raw->total_time, USEC_PER_MSEC) >= polling_ms ||
+	    !avg->total_time) {
+		*avg = *raw;
+		return;
+	}
+
+	/* Truncate the oldest history first.
+	 *
+	 * Because we keep the history with a single devfreq_dev_status,
+	 * rather than a list of devfreq_dev_status, we have to assume freq
+	 * and load are the same over avg->total_time.  We can scale down
+	 * avg->busy_time and avg->total_time by the same factor to drop
+	 * history.
+	 */
+	if (div_u64(avg->total_time + raw->total_time, USEC_PER_MSEC) >=
+			max_history_ms) {
+		const u32 new_total_time = polling_ms * USEC_PER_MSEC -
+			raw->total_time;
+		avg->busy_time = div_u64(
+				mul_u32_u32(avg->busy_time, new_total_time),
+				avg->total_time);
+		avg->total_time = new_total_time;
+	}
+
+	/* compute the average freq over avg->total_time + raw->total_time */
+	avg_freq = mul_u32_u32(avg->current_frequency, avg->total_time);
+	avg_freq += mul_u32_u32(raw->current_frequency, raw->total_time);
+	do_div(avg_freq, avg->total_time + raw->total_time);
+
+	avg->current_frequency = avg_freq;
+	avg->busy_time += raw->busy_time;
+	avg->total_time += raw->total_time;
+}
+
 static int msm_devfreq_get_dev_status(struct device *dev,
 		struct devfreq_dev_status *status)
 {
 	struct msm_gpu *gpu = dev_to_gpu(dev);
+	struct devfreq_dev_status raw;
 
-	get_raw_dev_status(gpu, status);
+	get_raw_dev_status(gpu, &raw);
+	update_average_dev_status(gpu, &raw);
+	*status = gpu->devfreq.average_status;
 
 	return 0;
 }
-- 
2.36.0.rc0.470.gd361397f0d-goog

Re: [PATCH 3/3] drm/msm: return the average load over the polling period

[Chia-I Wu]

On Fri, Apr 15, 2022 at 5:33 PM Chia-I Wu <olvaffe@gmail.com> wrote:
>
> simple_ondemand interacts poorly with clamp_to_idle.  It only looks at
> the load since the last get_dev_status call, while it should really look
> at the load over polling_ms.  When clamp_to_idle true, it almost always
> picks the lowest frequency on active because the gpu is idle between
> msm_devfreq_idle/msm_devfreq_active.
>
> This logic could potentially be moved into devfreq core.
The idea is to extend devfreq_simple_ondemand_data to specify whether
devfreq_simple_ondemand_func should use "last status" or "average
status" to determine the target frequency.  devfreq core will need to
store "struct devfreq_dev_status average_status", which will be
updated when a device uses simple_ondemand and asks for average_status
instead of last_status.



>
> Fixes: 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS constraints")
> Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
> Cc: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/gpu/drm/msm/msm_gpu.h         |  3 ++
>  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 ++++++++++++++++++++++++++-
>  2 files changed, 62 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> index 389c6dab751b..143c56f5185b 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.h
> +++ b/drivers/gpu/drm/msm/msm_gpu.h
> @@ -9,6 +9,7 @@
>
>  #include <linux/adreno-smmu-priv.h>
>  #include <linux/clk.h>
> +#include <linux/devfreq.h>
>  #include <linux/interconnect.h>
>  #include <linux/pm_opp.h>
>  #include <linux/regulator/consumer.h>
> @@ -117,6 +118,8 @@ struct msm_gpu_devfreq {
>         /** idle_time: Time of last transition to idle: */
>         ktime_t idle_time;
>
> +       struct devfreq_dev_status average_status;
> +
>         /**
>          * idle_work:
>          *
> diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> index f531015107c3..d2539ca78c29 100644
> --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> @@ -9,6 +9,7 @@
>
>  #include <linux/devfreq.h>
>  #include <linux/devfreq_cooling.h>
> +#include <linux/math64.h>
>  #include <linux/units.h>
>
>  /*
> @@ -75,12 +76,69 @@ static void get_raw_dev_status(struct msm_gpu *gpu,
>         status->busy_time = busy_time;
>  }
>
> +static void update_average_dev_status(struct msm_gpu *gpu,
> +               const struct devfreq_dev_status *raw)
> +{
> +       struct msm_gpu_devfreq *df = &gpu->devfreq;
> +       const u32 polling_ms = df->devfreq->profile->polling_ms;
> +       const u32 max_history_ms = polling_ms * 11 / 10;
> +       struct devfreq_dev_status *avg = &df->average_status;
> +       u64 avg_freq;
> +
> +       /* simple_ondemand governor interacts poorly with gpu->clamp_to_idle.
> +        * When we enforce the constraint on idle, it calls get_dev_status
> +        * which would normally reset the stats.  When we remove the
> +        * constraint on active, it calls get_dev_status again where busy_time
> +        * would be 0.
> +        *
> +        * To remedy this, we always return the average load over the past
> +        * polling_ms.
> +        */
> +
> +       /* raw is longer than polling_ms or avg has no history */
> +       if (div_u64(raw->total_time, USEC_PER_MSEC) >= polling_ms ||
> +           !avg->total_time) {
> +               *avg = *raw;
> +               return;
> +       }
> +
> +       /* Truncate the oldest history first.
> +        *
> +        * Because we keep the history with a single devfreq_dev_status,
> +        * rather than a list of devfreq_dev_status, we have to assume freq
> +        * and load are the same over avg->total_time.  We can scale down
> +        * avg->busy_time and avg->total_time by the same factor to drop
> +        * history.
> +        */
> +       if (div_u64(avg->total_time + raw->total_time, USEC_PER_MSEC) >=
> +                       max_history_ms) {
> +               const u32 new_total_time = polling_ms * USEC_PER_MSEC -
> +                       raw->total_time;
> +               avg->busy_time = div_u64(
> +                               mul_u32_u32(avg->busy_time, new_total_time),
> +                               avg->total_time);
> +               avg->total_time = new_total_time;
> +       }
> +
> +       /* compute the average freq over avg->total_time + raw->total_time */
> +       avg_freq = mul_u32_u32(avg->current_frequency, avg->total_time);
> +       avg_freq += mul_u32_u32(raw->current_frequency, raw->total_time);
> +       do_div(avg_freq, avg->total_time + raw->total_time);
> +
> +       avg->current_frequency = avg_freq;
> +       avg->busy_time += raw->busy_time;
> +       avg->total_time += raw->total_time;
> +}
> +
>  static int msm_devfreq_get_dev_status(struct device *dev,
>                 struct devfreq_dev_status *status)
>  {
>         struct msm_gpu *gpu = dev_to_gpu(dev);
> +       struct devfreq_dev_status raw;
>
> -       get_raw_dev_status(gpu, status);
> +       get_raw_dev_status(gpu, &raw);
> +       update_average_dev_status(gpu, &raw);
> +       *status = gpu->devfreq.average_status;
>
>         return 0;
>  }
> --
> 2.36.0.rc0.470.gd361397f0d-goog
>

Re: [PATCH 3/3] drm/msm: return the average load over the polling period

[Chia-I Wu]

On Fri, Apr 15, 2022 at 5:33 PM Chia-I Wu <olvaffe@gmail.com> wrote:
>
> simple_ondemand interacts poorly with clamp_to_idle.  It only looks at
> the load since the last get_dev_status call, while it should really look
> at the load over polling_ms.  When clamp_to_idle true, it almost always
> picks the lowest frequency on active because the gpu is idle between
> msm_devfreq_idle/msm_devfreq_active.
>
> This logic could potentially be moved into devfreq core.
The idea is to extend devfreq_simple_ondemand_data to specify whether
devfreq_simple_ondemand_func should use "last status" or "average
status" to determine the target frequency.  devfreq core will need to
store "struct devfreq_dev_status average_status", which will be
updated when a device uses simple_ondemand and asks for average_status
instead of last_status.



>
> Fixes: 7c0ffcd40b16 ("drm/msm/gpu: Respect PM QoS constraints")
> Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
> Cc: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/gpu/drm/msm/msm_gpu.h         |  3 ++
>  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 60 ++++++++++++++++++++++++++-
>  2 files changed, 62 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> index 389c6dab751b..143c56f5185b 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.h
> +++ b/drivers/gpu/drm/msm/msm_gpu.h
> @@ -9,6 +9,7 @@
>
>  #include <linux/adreno-smmu-priv.h>
>  #include <linux/clk.h>
> +#include <linux/devfreq.h>
>  #include <linux/interconnect.h>
>  #include <linux/pm_opp.h>
>  #include <linux/regulator/consumer.h>
> @@ -117,6 +118,8 @@ struct msm_gpu_devfreq {
>         /** idle_time: Time of last transition to idle: */
>         ktime_t idle_time;
>
> +       struct devfreq_dev_status average_status;
> +
>         /**
>          * idle_work:
>          *
> diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> index f531015107c3..d2539ca78c29 100644
> --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> @@ -9,6 +9,7 @@
>
>  #include <linux/devfreq.h>
>  #include <linux/devfreq_cooling.h>
> +#include <linux/math64.h>
>  #include <linux/units.h>
>
>  /*
> @@ -75,12 +76,69 @@ static void get_raw_dev_status(struct msm_gpu *gpu,
>         status->busy_time = busy_time;
>  }
>
> +static void update_average_dev_status(struct msm_gpu *gpu,
> +               const struct devfreq_dev_status *raw)
> +{
> +       struct msm_gpu_devfreq *df = &gpu->devfreq;
> +       const u32 polling_ms = df->devfreq->profile->polling_ms;
> +       const u32 max_history_ms = polling_ms * 11 / 10;
> +       struct devfreq_dev_status *avg = &df->average_status;
> +       u64 avg_freq;
> +
> +       /* simple_ondemand governor interacts poorly with gpu->clamp_to_idle.
> +        * When we enforce the constraint on idle, it calls get_dev_status
> +        * which would normally reset the stats.  When we remove the
> +        * constraint on active, it calls get_dev_status again where busy_time
> +        * would be 0.
> +        *
> +        * To remedy this, we always return the average load over the past
> +        * polling_ms.
> +        */
> +
> +       /* raw is longer than polling_ms or avg has no history */
> +       if (div_u64(raw->total_time, USEC_PER_MSEC) >= polling_ms ||
> +           !avg->total_time) {
> +               *avg = *raw;
> +               return;
> +       }
> +
> +       /* Truncate the oldest history first.
> +        *
> +        * Because we keep the history with a single devfreq_dev_status,
> +        * rather than a list of devfreq_dev_status, we have to assume freq
> +        * and load are the same over avg->total_time.  We can scale down
> +        * avg->busy_time and avg->total_time by the same factor to drop
> +        * history.
> +        */
> +       if (div_u64(avg->total_time + raw->total_time, USEC_PER_MSEC) >=
> +                       max_history_ms) {
> +               const u32 new_total_time = polling_ms * USEC_PER_MSEC -
> +                       raw->total_time;
> +               avg->busy_time = div_u64(
> +                               mul_u32_u32(avg->busy_time, new_total_time),
> +                               avg->total_time);
> +               avg->total_time = new_total_time;
> +       }
> +
> +       /* compute the average freq over avg->total_time + raw->total_time */
> +       avg_freq = mul_u32_u32(avg->current_frequency, avg->total_time);
> +       avg_freq += mul_u32_u32(raw->current_frequency, raw->total_time);
> +       do_div(avg_freq, avg->total_time + raw->total_time);
> +
> +       avg->current_frequency = avg_freq;
> +       avg->busy_time += raw->busy_time;
> +       avg->total_time += raw->total_time;
> +}
> +
>  static int msm_devfreq_get_dev_status(struct device *dev,
>                 struct devfreq_dev_status *status)
>  {
>         struct msm_gpu *gpu = dev_to_gpu(dev);
> +       struct devfreq_dev_status raw;
>
> -       get_raw_dev_status(gpu, status);
> +       get_raw_dev_status(gpu, &raw);
> +       update_average_dev_status(gpu, &raw);
> +       *status = gpu->devfreq.average_status;
>
>         return 0;
>  }
> --
> 2.36.0.rc0.470.gd361397f0d-goog
>