drm/panfrost: Simplify devfreq utilisation tracking

Instead of tracking per-slot utilisation track a single value for the
entire GPU. Ultimately it doesn't matter if the GPU is busy with only
vertex or a combination of vertex and fragment processing - if it's busy
then it's busy and devfreq should be scaling appropriately.

This also makes way for being able to submit multiple jobs per slot
which requires more values than the original boolean per slot.

Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191025134143.14324-3-steven.price@arm.com

1 files changed, 25 insertions, 39 deletions

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
index 7ded282a5ca8..4c4e8a30a1ac 100644
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
@@ -13,7 +13,7 @@
 #include "panfrost_gpu.h"
 #include "panfrost_regs.h"
 
-static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, int slot);
+static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev);
 
 static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
 				   u32 flags)
@@ -32,37 +32,23 @@ static int panfrost_devfreq_target(struct device *dev, unsigned long *freq,
 
 static void panfrost_devfreq_reset(struct panfrost_device *pfdev)
 {
-	ktime_t now = ktime_get();
-	int i;
-
-	for (i = 0; i < NUM_JOB_SLOTS; i++) {
-		pfdev->devfreq.slot[i].busy_time = 0;
-		pfdev->devfreq.slot[i].idle_time = 0;
-		pfdev->devfreq.slot[i].time_last_update = now;
-	}
+	pfdev->devfreq.busy_time = 0;
+	pfdev->devfreq.idle_time = 0;
+	pfdev->devfreq.time_last_update = ktime_get();
 }
 
 static int panfrost_devfreq_get_dev_status(struct device *dev,
 					   struct devfreq_dev_status *status)
 {
 	struct panfrost_device *pfdev = dev_get_drvdata(dev);
-	int i;
 
-	for (i = 0; i < NUM_JOB_SLOTS; i++) {
-		panfrost_devfreq_update_utilization(pfdev, i);
-	}
+	panfrost_devfreq_update_utilization(pfdev);
 
 	status->current_frequency = clk_get_rate(pfdev->clock);
-	status->total_time = ktime_to_ns(ktime_add(pfdev->devfreq.slot[0].busy_time,
-						   pfdev->devfreq.slot[0].idle_time));
-
-	status->busy_time = 0;
-	for (i = 0; i < NUM_JOB_SLOTS; i++) {
-		status->busy_time += ktime_to_ns(pfdev->devfreq.slot[i].busy_time);
-	}
+	status->total_time = ktime_to_ns(ktime_add(pfdev->devfreq.busy_time,
+						   pfdev->devfreq.idle_time));
 
-	/* We're scheduling only to one core atm, so don't divide for now */
-	/* status->busy_time /= NUM_JOB_SLOTS; */
+	status->busy_time = ktime_to_ns(pfdev->devfreq.busy_time);
 
 	panfrost_devfreq_reset(pfdev);
 
@@ -134,14 +120,10 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
 
 void panfrost_devfreq_resume(struct panfrost_device *pfdev)
 {
-	int i;
-
 	if (!pfdev->devfreq.devfreq)
 		return;
 
 	panfrost_devfreq_reset(pfdev);
-	for (i = 0; i < NUM_JOB_SLOTS; i++)
-		pfdev->devfreq.slot[i].busy = false;
 
 	devfreq_resume_device(pfdev->devfreq.devfreq);
 }
@@ -154,9 +136,8 @@ void panfrost_devfreq_suspend(struct panfrost_device *pfdev)
 	devfreq_suspend_device(pfdev->devfreq.devfreq);
 }
 
-static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, int slot)
+static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev)
 {
-	struct panfrost_devfreq_slot *devfreq_slot = &pfdev->devfreq.slot[slot];
 	ktime_t now;
 	ktime_t last;
 
@@ -164,22 +145,27 @@ static void panfrost_devfreq_update_utilization(struct panfrost_device *pfdev, i
 		return;
 
 	now = ktime_get();
-	last = pfdev->devfreq.slot[slot].time_last_update;
+	last = pfdev->devfreq.time_last_update;
 
-	/* If we last recorded a transition to busy, we have been idle since */
-	if (devfreq_slot->busy)
-		pfdev->devfreq.slot[slot].busy_time += ktime_sub(now, last);
+	if (atomic_read(&pfdev->devfreq.busy_count) > 0)
+		pfdev->devfreq.busy_time += ktime_sub(now, last);
 	else
-		pfdev->devfreq.slot[slot].idle_time += ktime_sub(now, last);
+		pfdev->devfreq.idle_time += ktime_sub(now, last);
+
+	pfdev->devfreq.time_last_update = now;
+}
 
-	pfdev->devfreq.slot[slot].time_last_update = now;
+void panfrost_devfreq_record_busy(struct panfrost_device *pfdev)
+{
+	panfrost_devfreq_update_utilization(pfdev);
+	atomic_inc(&pfdev->devfreq.busy_count);
 }
 
-/* The job scheduler is expected to call this at every transition busy <-> idle */
-void panfrost_devfreq_record_transition(struct panfrost_device *pfdev, int slot)
+void panfrost_devfreq_record_idle(struct panfrost_device *pfdev)
 {
-	struct panfrost_devfreq_slot *devfreq_slot = &pfdev->devfreq.slot[slot];
+	int count;
 
-	panfrost_devfreq_update_utilization(pfdev, slot);
-	devfreq_slot->busy = !devfreq_slot->busy;
+	panfrost_devfreq_update_utilization(pfdev);
+	count = atomic_dec_if_positive(&pfdev->devfreq.busy_count);
+	WARN_ON(count < 0);
 }