linux-kernel - [PATCH v2 1/3] drm/panfrost: Add PM runtime flag

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Message-ID: <20250403055210.54486-2-simons.philippe@gmail.com>
Date: Thu,  3 Apr 2025 07:52:08 +0200
From: Philippe Simons <simons.philippe@...il.com>
To: Boris Brezillon <boris.brezillon@...labora.com>,
	Rob Herring <robh@...nel.org>,
	Steven Price <steven.price@....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>,
	Philipp Zabel <p.zabel@...gutronix.de>
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	linux-sunxi@...ts.linux.dev,
	Andre Przywara <andre.przywara@....com>,
	Jernej Škrabec <jernej.skrabec@...il.com>
Subject: [PATCH v2 1/3] drm/panfrost: Add PM runtime flag

When the GPU is the only device attached to a single power domain,
core genpd disable and enable it when gpu enter and leave runtime suspend.

Some power-domain requires a sequence before disabled,
and the reverse when enabled.

Add GPU_PM_RT flag, and implement in
panfrost_device_runtime_suspend/resume.

Reviewed-by: Steven Price <steven.price@....com>
Signed-off-by: Philippe Simons <simons.philippe@...il.com>
---
 drivers/gpu/drm/panfrost/panfrost_device.c | 33 ++++++++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_device.h |  3 ++
 2 files changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index a45e4addcc19..93d48e97ce10 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -406,11 +406,36 @@ void panfrost_device_reset(struct panfrost_device *pfdev)
 static int panfrost_device_runtime_resume(struct device *dev)
 {
 	struct panfrost_device *pfdev = dev_get_drvdata(dev);
+	int ret;
+
+	if (pfdev->comp->pm_features & BIT(GPU_PM_RT)) {
+		ret = reset_control_deassert(pfdev->rstc);
+		if (ret)
+			return ret;
+
+		ret = clk_enable(pfdev->clock);
+		if (ret)
+			goto err_clk;
+
+		if (pfdev->bus_clock) {
+			ret = clk_enable(pfdev->bus_clock);
+			if (ret)
+				goto err_bus_clk;
+		}
+	}
 
 	panfrost_device_reset(pfdev);
 	panfrost_devfreq_resume(pfdev);
 
 	return 0;
+
+err_bus_clk:
+	if (pfdev->comp->pm_features & BIT(GPU_PM_RT))
+		clk_disable(pfdev->clock);
+err_clk:
+	if (pfdev->comp->pm_features & BIT(GPU_PM_RT))
+		reset_control_assert(pfdev->rstc);
+	return ret;
 }
 
 static int panfrost_device_runtime_suspend(struct device *dev)
@@ -426,6 +451,14 @@ static int panfrost_device_runtime_suspend(struct device *dev)
 	panfrost_gpu_suspend_irq(pfdev);
 	panfrost_gpu_power_off(pfdev);
 
+	if (pfdev->comp->pm_features & BIT(GPU_PM_RT)) {
+		if (pfdev->bus_clock)
+			clk_disable(pfdev->bus_clock);
+
+		clk_disable(pfdev->clock);
+		reset_control_assert(pfdev->rstc);
+	}
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index cffcb0ac7c11..861555ceea65 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -36,10 +36,13 @@ enum panfrost_drv_comp_bits {
  * enum panfrost_gpu_pm - Supported kernel power management features
  * @GPU_PM_CLK_DIS:  Allow disabling clocks during system suspend
  * @GPU_PM_VREG_OFF: Allow turning off regulators during system suspend
+ * @GPU_PM_RT: Allow disabling clocks and asserting the reset control during
+ *  system runtime suspend
  */
 enum panfrost_gpu_pm {
 	GPU_PM_CLK_DIS,
 	GPU_PM_VREG_OFF,
+	GPU_PM_RT
 };
 
 struct panfrost_features {
-- 
2.49.0