linux-kernel - [PATCH v6 6/7] drm/panthor: Use existing OPP table if present

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Message-Id: <20251003-mt8196-gpufreq-v6-6-76498ad61d9e@collabora.com>
Date: Fri, 03 Oct 2025 22:15:08 +0200
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Boris Brezillon <boris.brezillon@...labora.com>, 
 Jassi Brar <jassisinghbrar@...il.com>, Chia-I Wu <olvaffe@...il.com>, 
 Chen-Yu Tsai <wenst@...omium.org>, Steven Price <steven.price@....com>, 
 Liviu Dudau <liviu.dudau@....com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, Kees Cook <kees@...nel.org>, 
 "Gustavo A. R. Silva" <gustavoars@...nel.org>, 
 Ulf Hansson <ulf.hansson@...aro.org>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 linux-hardening@...r.kernel.org, linux-pm@...r.kernel.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH v6 6/7] 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.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
 drivers/gpu/drm/panthor/panthor_devfreq.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_devfreq.c b/drivers/gpu/drm/panthor/panthor_devfreq.c
index 978f193a2aee561fadd9a976e9b1417118260889..6beb6170d6eea3dd65880dfe64a61abbdd5f08da 100644
--- a/drivers/gpu/drm/panthor/panthor_devfreq.c
+++ b/drivers/gpu/drm/panthor/panthor_devfreq.c
@@ -143,6 +143,7 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
 	struct panthor_devfreq *pdevfreq;
 	struct dev_pm_opp *opp;
 	unsigned long cur_freq;
+	struct opp_table *t;
 	unsigned long freq = ULONG_MAX;
 	int ret;

@@ -152,18 +153,23 @@ int panthor_devfreq_init(struct panthor_device *ptdev)

 	ptdev->devfreq = pdevfreq;

-	ret = devm_pm_opp_set_regulators(dev, reg_names);
-	if (ret) {
-		if (ret != -EPROBE_DEFER)
-			DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
-
-		return ret;
+	t = dev_pm_opp_get_opp_table(dev);
+	if (IS_ERR_OR_NULL(t)) {
+		ret = devm_pm_opp_set_regulators(dev, reg_names);
+		if (ret) {
+			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(t);
 	}

-	ret = devm_pm_opp_of_add_table(dev);
-	if (ret)
-		return ret;
-
 	spin_lock_init(&pdevfreq->lock);

 	panthor_devfreq_reset(pdevfreq);

-- 
2.51.0