drm/panfrost: Add governor data with pre-defined thresholds

The simple_ondemand devfreq governor uses two thresholds to decide about
the frequency change: upthreshold, downdifferential. These two tunable
change the behavior of the governor decision, e.g. how fast to increase
the frequency or how rapidly limit the frequency. This patch adds needed
governor data with thresholds values gathered experimentally in different
workloads.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121170445.19761-1-lukasz.luba@arm.com

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
index 56b3f5935703ac88d9c904041fb953dc045df349..7c5ffc81dce1ae0d0c783e01c25dee625b79089c 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
@@ -130,8 +130,16 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
        panfrost_devfreq_profile.initial_freq = cur_freq;
        dev_pm_opp_put(opp);
 
+       /*
+        * Setup default thresholds for the simple_ondemand governor.
+        * The values are chosen based on experiments.
+        */
+       pfdevfreq->gov_data.upthreshold = 45;
+       pfdevfreq->gov_data.downdifferential = 5;
+
        devfreq = devm_devfreq_add_device(dev, &panfrost_devfreq_profile,
-                                         DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
+                                         DEVFREQ_GOV_SIMPLE_ONDEMAND,
+                                         &pfdevfreq->gov_data);
        if (IS_ERR(devfreq)) {
                DRM_DEV_ERROR(dev, "Couldn't initialize GPU devfreq\n");
                ret = PTR_ERR(devfreq);

diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.h b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
index db6ea48e21f9c05178ae64bde882394169a5f4bd..1e2a4de941aa68addfbb7763542cb57192bf00dc 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_devfreq.h
+++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
@@ -4,6 +4,7 @@
 #ifndef __PANFROST_DEVFREQ_H__
 #define __PANFROST_DEVFREQ_H__
 
+#include <linux/devfreq.h>
 #include <linux/spinlock.h>
 #include <linux/ktime.h>
 
@@ -17,6 +18,7 @@ struct panfrost_devfreq {
        struct devfreq *devfreq;
        struct opp_table *regulators_opp_table;
        struct thermal_cooling_device *cooling;
+       struct devfreq_simple_ondemand_data gov_data;
        bool opp_of_table_added;
 
        ktime_t busy_time;