drm/panthor: Use existing OPP table if present

On SoCs where the GPU's power-domain is in charge of setting performance
levels, the OPP table of the GPU node will have already been populated
during said power-domain's attach_dev operation.

To avoid initialising an OPP table twice, only set the OPP regulator and
the OPPs from DT if there's no OPP table present.

Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Link: https://patch.msgid.link/20251017-mt8196-gpufreq-v8-4-98fc1cc566a1@collabora.com
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.c b/drivers/gpu/drm/panthor/panthor_devfreq.c
index d4a92f9b84ae9ad6b5ae88b73cab5b1ac669c437..2249b41ca4afe00d27a61c889dbb9f319d48de0c 100644 (file)
--- a/drivers/gpu/drm/panthor/panthor_devfreq.c
+++ b/drivers/gpu/drm/panthor/panthor_devfreq.c
@@ -142,6 +142,7 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
        struct thermal_cooling_device *cooling;
        struct device *dev = ptdev->base.dev;
        struct panthor_devfreq *pdevfreq;
+       struct opp_table *table;
        struct dev_pm_opp *opp;
        unsigned long cur_freq;
        unsigned long freq = ULONG_MAX;
@@ -153,17 +154,30 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
 
        ptdev->devfreq = pdevfreq;
 
-       ret = devm_pm_opp_set_regulators(dev, reg_names);
-       if (ret && ret != -ENODEV) {
-               if (ret != -EPROBE_DEFER)
-                       DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
-               return ret;
+       /*
+        * The power domain associated with the GPU may have already added an
+        * OPP table, complete with OPPs, as part of the platform bus
+        * initialization. If this is the case, the power domain is in charge of
+        * also controlling the performance, with a set_performance callback.
+        * Only add a new OPP table from DT if there isn't such a table present
+        * already.
+        */
+       table = dev_pm_opp_get_opp_table(dev);
+       if (IS_ERR_OR_NULL(table)) {
+               ret = devm_pm_opp_set_regulators(dev, reg_names);
+               if (ret && ret != -ENODEV) {
+                       if (ret != -EPROBE_DEFER)
+                               DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
+                       return ret;
+               }
+
+               ret = devm_pm_opp_of_add_table(dev);
+               if (ret)
+                       return ret;
+       } else {
+               dev_pm_opp_put_opp_table(table);
        }
 
-       ret = devm_pm_opp_of_add_table(dev);
-       if (ret)
-               return ret;
-
        spin_lock_init(&pdevfreq->lock);
 
        panthor_devfreq_reset(pdevfreq);