[PATCH 4/9] drm/panthor: Implement optional reset

Marek Vasut
2025-02-27T17:00:53Z

The instance of the GPU populated in Freescale i.MX95 does require
release from reset by writing into a single GPUMIX block controller
GPURESET register bit 0. Implement support for one optional reset.

Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Steven Price <steven.price@arm.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: devicetree@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: imx@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
---
drivers/gpu/drm/panthor/Kconfig | 1 +
drivers/gpu/drm/panthor/panthor_device.c | 23 +++++++++++++++++++++++
drivers/gpu/drm/panthor/panthor_device.h | 3 +++
3 files changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/panthor/Kconfig b/drivers/gpu/drm/panthor/Kconfig
index 55b40ad07f3b0..ab62bd6a0750f 100644
--- a/drivers/gpu/drm/panthor/Kconfig
+++ b/drivers/gpu/drm/panthor/Kconfig
@@ -14,6 +14,7 @@ config DRM_PANTHOR
select IOMMU_IO_PGTABLE_LPAE
select IOMMU_SUPPORT
select PM_DEVFREQ
+ select RESET_SIMPLE if SOC_IMX9
help
DRM driver for ARM Mali CSF-based GPUs.

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index a9da1d1eeb707..51ee9cae94504 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -64,6 +64,17 @@ static int panthor_clk_init(struct panthor_device *ptdev)
return 0;
}

+static int panthor_reset_init(struct panthor_device *ptdev)
+{
+ ptdev->resets = devm_reset_control_get_optional_exclusive_deasserted(ptdev->base.dev, NULL);
+ if (IS_ERR(ptdev->resets))
+ return dev_err_probe(ptdev->base.dev,
+ PTR_ERR(ptdev->resets),
+ "get reset failed");
+
+ return 0;
+}
+
void panthor_device_unplug(struct panthor_device *ptdev)
{
/* This function can be called from two different path: the reset work
@@ -217,6 +228,10 @@ int panthor_device_init(struct panthor_device *ptdev)
if (ret)
return ret;

+ ret = panthor_reset_init(ptdev);
+ if (ret)
+ return ret;
+
ret = panthor_devfreq_init(ptdev);
if (ret)
return ret;
@@ -470,6 +485,10 @@ int panthor_device_resume(struct device *dev)
if (ret)
goto err_disable_stacks_clk;

+ ret = reset_control_deassert(ptdev->resets);
+ if (ret)
+ goto err_disable_coregroup_clk;
+
panthor_devfreq_resume(ptdev);

if (panthor_device_is_initialized(ptdev) &&
@@ -512,6 +531,9 @@ int panthor_device_resume(struct device *dev)

err_suspend_devfreq:
panthor_devfreq_suspend(ptdev);
+ reset_control_assert(ptdev->resets);
+
+err_disable_coregroup_clk:
clk_disable_unprepare(ptdev->clks.coregroup);

err_disable_stacks_clk:
@@ -563,6 +585,7 @@ int panthor_device_suspend(struct device *dev)

panthor_devfreq_suspend(ptdev);

+ reset_control_assert(ptdev->resets);
clk_disable_unprepare(ptdev->clks.coregroup);
clk_disable_unprepare(ptdev->clks.stacks);
clk_disable_unprepare(ptdev->clks.core);
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index da6574021664b..fea3a05778e2e 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -111,6 +111,9 @@ struct panthor_device {
struct clk *coregroup;
} clks;

+ /** @resets: GPU reset. */
+ struct reset_control *resets;
+
/** @coherent: True if the CPU/GPU are memory coherent. */
bool coherent;

--
2.47.2