[RFC PATCH] media: mediatek: mdp: Keep component suppliers powered while streaming

[RFC PATCH] media: mediatek: mdp: Keep component suppliers powered while streaming

[getfeus]

Hi,

Following up on my earlier report ("MT8173 legacy MDP: PROCESS_ACK
status 0 but CAPTURE remains unchanged"), I dug into the runtime-PM
dependencies on an MT8173 Elm Chromebook.

The legacy MDP driver manages the clocks for its sibling blocks
directly from the RDMA0 master, but it does not establish runtime-PM
dependencies from the master to those devices. As a result, their
suppliers are not all kept active during processing. In particular,
LARB4 stays suspended.

In the failing case, the firmware reports success and both buffers
complete, yet the CAPTURE planes remain untouched, matching the
pre-queue canary. Keeping LARB4 active before the first job changes
the output to a byte-exact copy.

The proposed fix binds the sibling blocks as components and adds
runtime-PM device links from the master to them. Their existing
IOMMU/LARB supplier links then propagate the required PM references.
Engine clock handling stays in the master, and the M2M device is
registered only after all required components have bound. The existing
fallback path for legacy child-node DTs is retained.

I also reproduced an IOMMU read fault on LARB4 port 4 (MDP_RDMA1)
after closing a failed job and unmapping its buffers. Tracing
associated the reported fault page with that job's input Y allocation.
No second PROCESS command was submitted before the fault was reported
during the subsequent LARB4 reactivation sequence.

The patch fixes the missing PM dependencies. All ten conversion tests
passed with pixel-exact output and no IOMMU faults, without manually
forcing LARB4 on.

Tested on Elm (next-20261105-based kernel, VPU firmware v1.2.0):

- Seven NV12M 640x360 copy jobs produced byte-exact Y/UV output.
- Three saved MT21C 640x384 to YUV420M 640x360 conversions matched the
software-decoded reference across all visible Y/U/V samples.
- Testing covered both temporary module loading and loading the
candidate during boot.
- LARB4 remained under the "auto" PM policy, became active during
streaming, and suspended again after streaming stopped.
- Three STREAMON-without-buffers checks returned the expected EINVAL,
with no additional PROCESS commands or observed PM cleanup failures.
- The PM changes apply and build cleanly against next-20261105 without
the diagnostic instrumentation.

The diff below is based on current linux-next (793807ca13bf). Compared
with the tested next-20261105 files, the only intervening changes in
these files are two devm_kzalloc_obj() substitutions. Those upstream
changes are retained; the proposed PM changes are unchanged.

System suspend/resume, other boards, legacy child-node DTs, and
probe/allocation error-injection paths have not been tested.

Does this look like the right way to model the runtime-PM dependencies
for the legacy MDP components? I'd especially appreciate feedback on
the device-link lifetime and component bind/unbind ordering.

I have the userspace reproducer, deterministic test pattern generator,
and ftrace logs available if useful.

Thanks,
Youngjoon Lee

Signed-off-by: Youngjoon Lee <getfeus@gmail.com>
---
 drivers/media/platform/mediatek/mdp/Makefile       |  1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h |  1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_core.c | 91 +++++++++++++++++++---
 drivers/media/platform/mediatek/mdp/mtk_mdp_core.h |  2 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c   | 81 +++++++++++++++++++
 5 files changed, 165 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/mediatek/mdp/Makefile
b/drivers/media/platform/mediatek/mdp/Makefile
index b7c16eb..c3f3a74 100644
--- a/drivers/media/platform/mediatek/mdp/Makefile
+++ b/drivers/media/platform/mediatek/mdp/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 mtk-mdp-y += mtk_mdp_core.o
+mtk-mdp-y += mtk_mdp_pm.o
 mtk-mdp-y += mtk_mdp_comp.o
 mtk-mdp-y += mtk_mdp_m2m.o
 mtk-mdp-y += mtk_mdp_regs.o
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
index ae41dd3..c9098d8 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
@@ -42,5 +42,6 @@ void mtk_mdp_comp_deinit(struct device *dev, struct
mtk_mdp_comp *comp);
 void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp);
 void mtk_mdp_comp_clock_off(struct device *dev, struct mtk_mdp_comp *comp);

+extern struct platform_driver mtk_mdp_pm_component_driver;

 #endif /* __MTK_MDP_COMP_H__ */
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
index c065cde..23bcaa8 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
@@ -6,6 +6,7 @@
  */

 #include <linux/clk.h>
+#include <linux/component.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
@@ -102,12 +103,50 @@ void mtk_mdp_unregister_component(struct mtk_mdp_dev *mdp,
 	list_del(&comp->node);
 }

+static int mtk_mdp_compare_component(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
+
+static void mtk_mdp_release_component(struct device *dev, void *data)
+{
+	of_node_put(data);
+}
+
+static int mtk_mdp_master_bind(struct device *dev)
+{
+	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+	int ret;
+
+	ret = component_bind_all(dev, mdp);
+	if (ret)
+		return ret;
+	ret = mtk_mdp_register_m2m_device(mdp);
+	if (ret)
+		component_unbind_all(dev, mdp);
+	return ret;
+}
+
+static void mtk_mdp_master_unbind(struct device *dev)
+{
+	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+
+	mtk_mdp_unregister_m2m_device(mdp);
+	component_unbind_all(dev, mdp);
+}
+
+static const struct component_master_ops mtk_mdp_master_ops = {
+	.bind = mtk_mdp_master_bind,
+	.unbind = mtk_mdp_master_unbind,
+};
+
 static int mtk_mdp_probe(struct platform_device *pdev)
 {
 	struct mtk_mdp_dev *mdp;
 	struct device *dev = &pdev->dev;
 	struct device_node *node, *parent;
 	struct mtk_mdp_comp *comp, *comp_temp;
+	struct component_match *match = NULL;
 	int ret = 0;

 	mdp = devm_kzalloc_obj(dev, *mdp);
@@ -132,6 +171,8 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		parent = dev->of_node->parent;
 	}

+	mdp->use_components = parent != dev->of_node;
+
 	/* Iterate over sibling MDP function blocks */
 	for_each_child_of_node(parent, node) {
 		const struct of_device_id *of_id;
@@ -163,6 +204,11 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		}

 		mtk_mdp_register_component(mdp, comp);
+		if (mdp->use_components && node != dev->of_node)
+			component_match_add_release(dev, &match,
+						    mtk_mdp_release_component,
+						    mtk_mdp_compare_component,
+						    of_node_get(node));
 	}

 	mdp->job_wq = create_singlethread_workqueue(MTK_MDP_MODULE_NAME);
@@ -187,12 +233,6 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		goto err_dev_register;
 	}

-	ret = mtk_mdp_register_m2m_device(mdp);
-	if (ret) {
-		v4l2_err(&mdp->v4l2_dev, "Failed to init mem2mem device\n");
-		goto err_m2m_register;
-	}
-
 	mdp->vpu_dev = vpu_get_plat_device(pdev);
 	if (!mdp->vpu_dev) {
 		dev_err(&pdev->dev, "Failed to get vpu device\n");
@@ -216,17 +256,25 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 	}

 	pm_runtime_enable(dev);
+	if (mdp->use_components)
+		ret = component_master_add_with_match(dev, &mtk_mdp_master_ops,
+						      match);
+	else
+		ret = mtk_mdp_register_m2m_device(mdp);
+	if (ret)
+		goto err_register_components;
 	dev_dbg(dev, "mdp-%d registered successfully\n", mdp->id);

 	return 0;

+err_register_components:
+	pm_runtime_disable(dev);
+	vb2_dma_contig_clear_max_seg_size(dev);
+
 err_reg_handler:
 	platform_device_put(mdp->vpu_dev);

 err_vpu_get_dev:
-	mtk_mdp_unregister_m2m_device(mdp);
-
-err_m2m_register:
 	v4l2_device_unregister(&mdp->v4l2_dev);

 err_dev_register:
@@ -252,10 +300,13 @@ static void mtk_mdp_remove(struct platform_device *pdev)
 	struct mtk_mdp_dev *mdp = platform_get_drvdata(pdev);
 	struct mtk_mdp_comp *comp, *comp_temp;

+	if (mdp->use_components)
+		component_master_del(&pdev->dev, &mtk_mdp_master_ops);
+	else
+		mtk_mdp_unregister_m2m_device(mdp);
 	pm_runtime_disable(&pdev->dev);
 	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 	platform_device_put(mdp->vpu_dev);
-	mtk_mdp_unregister_m2m_device(mdp);
 	v4l2_device_unregister(&mdp->v4l2_dev);

 	destroy_workqueue(mdp->wdt_wq);
@@ -319,7 +370,25 @@ static struct platform_driver mtk_mdp_driver = {
 	}
 };

-module_platform_driver(mtk_mdp_driver);
+static struct platform_driver * const mtk_mdp_drivers[] = {
+	&mtk_mdp_pm_component_driver,
+	&mtk_mdp_driver,
+};
+
+static int __init mtk_mdp_init(void)
+{
+	return platform_register_drivers(mtk_mdp_drivers,
+					 ARRAY_SIZE(mtk_mdp_drivers));
+}
+
+static void __exit mtk_mdp_exit(void)
+{
+	platform_unregister_drivers(mtk_mdp_drivers,
+				    ARRAY_SIZE(mtk_mdp_drivers));
+}
+
+module_init(mtk_mdp_init);
+module_exit(mtk_mdp_exit);

 MODULE_AUTHOR("Houlong Wei <houlong.wei@mediatek.com>");
 MODULE_DESCRIPTION("Mediatek image processor driver");
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
index a6e6dc3..c9004e4 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
@@ -133,6 +133,7 @@ struct mtk_mdp_variant {
  * struct mtk_mdp_dev - abstraction for image processor entity
  * @lock:	the mutex protecting this data structure
  * @vpulock:	the mutex protecting the communication with VPU
+ * @use_components: use sibling component PM supplier links
  * @pdev:	pointer to the image processor platform device
  * @variant:	the IP variant information
  * @id:		image processor device index (0..MTK_MDP_MAX_DEVS)
@@ -152,6 +153,7 @@ struct mtk_mdp_dev {
 	struct mutex			lock;
 	struct mutex			vpulock;
 	struct platform_device		*pdev;
+	bool				use_components;
 	struct mtk_mdp_variant		*variant;
 	u16				id;
 	struct list_head		comp_list;
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
new file mode 100644
index 0000000..a984f23
--- /dev/null
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Keep the DMA component suppliers powered for the master runtime lifetime. */
+#include <linux/component.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+struct mtk_mdp_pm_component {
+	struct device_link *link;
+};
+
+static int mtk_mdp_pm_bind(struct device *dev, struct device *master,
void *data)
+{
+	struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+	/* The component already has its IOMMU/LARB runtime-PM supplier link. */
+	comp->link = device_link_add(master, dev,
+				     DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+	return comp->link ? 0 : -ENOMEM;
+}
+
+static void mtk_mdp_pm_unbind(struct device *dev, struct device *master,
+			      void *data)
+{
+	struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+	device_link_del(comp->link);
+	comp->link = NULL;
+}
+
+static const struct component_ops mtk_mdp_pm_component_ops = {
+	.bind = mtk_mdp_pm_bind,
+	.unbind = mtk_mdp_pm_unbind,
+};
+
+static int mtk_mdp_pm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mtk_mdp_pm_component *comp;
+	int ret;
+
+	/* RDMA0 is the master; it must not become its own supplier. */
+	if (of_property_present(dev->of_node, "mediatek,vpu"))
+		return -ENODEV;
+	comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
+	if (!comp)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, comp);
+	pm_runtime_enable(dev);
+	ret = component_add(dev, &mtk_mdp_pm_component_ops);
+	if (ret)
+		pm_runtime_disable(dev);
+	return ret;
+}
+
+static void mtk_mdp_pm_remove(struct platform_device *pdev)
+{
+	component_del(&pdev->dev, &mtk_mdp_pm_component_ops);
+	pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id mtk_mdp_pm_of_match[] = {
+	{ .compatible = "mediatek,mt8173-mdp-rdma" },
+	{ .compatible = "mediatek,mt8173-mdp-rsz" },
+	{ .compatible = "mediatek,mt8173-mdp-wdma" },
+	{ .compatible = "mediatek,mt8173-mdp-wrot" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mtk_mdp_pm_of_match);
+
+struct platform_driver mtk_mdp_pm_component_driver = {
+	.probe = mtk_mdp_pm_probe,
+	.remove = mtk_mdp_pm_remove,
+	.driver = {
+		.name = "mtk-mdp-pm-component",
+		.of_match_table = mtk_mdp_pm_of_match,
+	},
+};

[PATCH RFC v2] media: mediatek: mdp: Keep component suppliers powered while streaming

[Youngjoon Lee via B4 Relay]

From: Youngjoon Lee <getfeus@gmail.com>

Sibling clocks are enabled without keeping their PM suppliers active.

On MT8173 Elm, LARB4 stays suspended and CAPTURE memory is unchanged.
The firmware reports success despite the unchanged CAPTURE buffers.

Bind sibling blocks and add runtime-PM links from the RDMA0 master.
Retain master clock handling and the legacy child-node DT fallback.

Signed-off-by: Youngjoon Lee <getfeus@gmail.com>
---
Hi,

This v2 is based on media-committers.git next (bf6c63ecc20a). The PM changes are unchanged from v1. The five resulting driver files are byte-for-byte identical to the clean candidate tested on Elm.

The archived v1 copy had reflowed diff headers, and its linux-next context also included two allocator-helper changes that are not yet in the media tree. This revision uses the media baseline and the b4 web submission endpoint. Local b4 shazam checks pass against both the bot's next and fixes commits.

The original failure returned successful firmware status and completed buffers while CAPTURE memory stayed unchanged. Binding the sibling components and linking their runtime PM to the master makes their IOMMU/LARB supplier dependencies follow streaming. Engine clock handling remains in the master.

While investigating, I also reproduced an RDMA1 IOMMU read fault associated with the previous job's unmapped input Y page, without a second PROCESS command. The patched tests below completed without IOMMU faults; I am not claiming to have observed the firmware's internal DMA completion timing.

Tested on Elm, next-20261105-based kernel, VPU firmware v1.2.0:
- Seven NV12M 640x360 copy jobs: byte-exact Y/UV output.
- Three saved MT21C 640x384 to YUV420M 640x360 jobs: every visible Y/U/V sample matched the software-decoded reference.
- Both temporary module loading and candidate loading during boot.
- LARB4 used the auto PM policy, woke during streaming, and suspended after streaming stopped.
- Three STREAMON-without-buffers checks: expected EINVAL, no extra PROCESS commands or observed PM cleanup failures.
- Clean module build without diagnostic hooks.

System suspend/resume, other boards, legacy child-node DTs, and probe/allocation failure injection remain untested.

Changes in v2:
- Rebase onto the media next tree; retain its allocator call context.
- Preserve diff formatting through the b4 submission path.
- Verify email extraction and application with b4 on both media branches.
- No PM logic changes.

I'd appreciate feedback on the runtime-PM device-link lifetime and component bind/unbind ordering. I have the reproducer, deterministic input, and ftrace logs available if useful.

Thanks,
Youngjoon Lee
---
 drivers/media/platform/mediatek/mdp/Makefile       |  1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h |  1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_core.c | 91 +++++++++++++++++++---
 drivers/media/platform/mediatek/mdp/mtk_mdp_core.h |  2 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c   | 81 +++++++++++++++++++
 5 files changed, 165 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/mediatek/mdp/Makefile b/drivers/media/platform/mediatek/mdp/Makefile
index b7c16eb..c3f3a74 100644
--- a/drivers/media/platform/mediatek/mdp/Makefile
+++ b/drivers/media/platform/mediatek/mdp/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 mtk-mdp-y += mtk_mdp_core.o
+mtk-mdp-y += mtk_mdp_pm.o
 mtk-mdp-y += mtk_mdp_comp.o
 mtk-mdp-y += mtk_mdp_m2m.o
 mtk-mdp-y += mtk_mdp_regs.o
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
index ae41dd3..c9098d8 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
@@ -42,5 +42,6 @@ void mtk_mdp_comp_deinit(struct device *dev, struct mtk_mdp_comp *comp);
 void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp);
 void mtk_mdp_comp_clock_off(struct device *dev, struct mtk_mdp_comp *comp);
 
+extern struct platform_driver mtk_mdp_pm_component_driver;
 
 #endif /* __MTK_MDP_COMP_H__ */
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
index 8432833..7d68ee5 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/component.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
@@ -102,12 +103,50 @@ void mtk_mdp_unregister_component(struct mtk_mdp_dev *mdp,
 	list_del(&comp->node);
 }
 
+static int mtk_mdp_compare_component(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
+
+static void mtk_mdp_release_component(struct device *dev, void *data)
+{
+	of_node_put(data);
+}
+
+static int mtk_mdp_master_bind(struct device *dev)
+{
+	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+	int ret;
+
+	ret = component_bind_all(dev, mdp);
+	if (ret)
+		return ret;
+	ret = mtk_mdp_register_m2m_device(mdp);
+	if (ret)
+		component_unbind_all(dev, mdp);
+	return ret;
+}
+
+static void mtk_mdp_master_unbind(struct device *dev)
+{
+	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+
+	mtk_mdp_unregister_m2m_device(mdp);
+	component_unbind_all(dev, mdp);
+}
+
+static const struct component_master_ops mtk_mdp_master_ops = {
+	.bind = mtk_mdp_master_bind,
+	.unbind = mtk_mdp_master_unbind,
+};
+
 static int mtk_mdp_probe(struct platform_device *pdev)
 {
 	struct mtk_mdp_dev *mdp;
 	struct device *dev = &pdev->dev;
 	struct device_node *node, *parent;
 	struct mtk_mdp_comp *comp, *comp_temp;
+	struct component_match *match = NULL;
 	int ret = 0;
 
 	mdp = devm_kzalloc(dev, sizeof(*mdp), GFP_KERNEL);
@@ -132,6 +171,8 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		parent = dev->of_node->parent;
 	}
 
+	mdp->use_components = parent != dev->of_node;
+
 	/* Iterate over sibling MDP function blocks */
 	for_each_child_of_node(parent, node) {
 		const struct of_device_id *of_id;
@@ -163,6 +204,11 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		}
 
 		mtk_mdp_register_component(mdp, comp);
+		if (mdp->use_components && node != dev->of_node)
+			component_match_add_release(dev, &match,
+						    mtk_mdp_release_component,
+						    mtk_mdp_compare_component,
+						    of_node_get(node));
 	}
 
 	mdp->job_wq = create_singlethread_workqueue(MTK_MDP_MODULE_NAME);
@@ -187,12 +233,6 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		goto err_dev_register;
 	}
 
-	ret = mtk_mdp_register_m2m_device(mdp);
-	if (ret) {
-		v4l2_err(&mdp->v4l2_dev, "Failed to init mem2mem device\n");
-		goto err_m2m_register;
-	}
-
 	mdp->vpu_dev = vpu_get_plat_device(pdev);
 	if (!mdp->vpu_dev) {
 		dev_err(&pdev->dev, "Failed to get vpu device\n");
@@ -216,17 +256,25 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 	}
 
 	pm_runtime_enable(dev);
+	if (mdp->use_components)
+		ret = component_master_add_with_match(dev, &mtk_mdp_master_ops,
+						      match);
+	else
+		ret = mtk_mdp_register_m2m_device(mdp);
+	if (ret)
+		goto err_register_components;
 	dev_dbg(dev, "mdp-%d registered successfully\n", mdp->id);
 
 	return 0;
 
+err_register_components:
+	pm_runtime_disable(dev);
+	vb2_dma_contig_clear_max_seg_size(dev);
+
 err_reg_handler:
 	platform_device_put(mdp->vpu_dev);
 
 err_vpu_get_dev:
-	mtk_mdp_unregister_m2m_device(mdp);
-
-err_m2m_register:
 	v4l2_device_unregister(&mdp->v4l2_dev);
 
 err_dev_register:
@@ -252,10 +300,13 @@ static void mtk_mdp_remove(struct platform_device *pdev)
 	struct mtk_mdp_dev *mdp = platform_get_drvdata(pdev);
 	struct mtk_mdp_comp *comp, *comp_temp;
 
+	if (mdp->use_components)
+		component_master_del(&pdev->dev, &mtk_mdp_master_ops);
+	else
+		mtk_mdp_unregister_m2m_device(mdp);
 	pm_runtime_disable(&pdev->dev);
 	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 	platform_device_put(mdp->vpu_dev);
-	mtk_mdp_unregister_m2m_device(mdp);
 	v4l2_device_unregister(&mdp->v4l2_dev);
 
 	destroy_workqueue(mdp->wdt_wq);
@@ -319,7 +370,25 @@ static struct platform_driver mtk_mdp_driver = {
 	}
 };
 
-module_platform_driver(mtk_mdp_driver);
+static struct platform_driver * const mtk_mdp_drivers[] = {
+	&mtk_mdp_pm_component_driver,
+	&mtk_mdp_driver,
+};
+
+static int __init mtk_mdp_init(void)
+{
+	return platform_register_drivers(mtk_mdp_drivers,
+					 ARRAY_SIZE(mtk_mdp_drivers));
+}
+
+static void __exit mtk_mdp_exit(void)
+{
+	platform_unregister_drivers(mtk_mdp_drivers,
+				    ARRAY_SIZE(mtk_mdp_drivers));
+}
+
+module_init(mtk_mdp_init);
+module_exit(mtk_mdp_exit);
 
 MODULE_AUTHOR("Houlong Wei <houlong.wei@mediatek.com>");
 MODULE_DESCRIPTION("Mediatek image processor driver");
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
index a6e6dc3..c9004e4 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
@@ -133,6 +133,7 @@ struct mtk_mdp_variant {
  * struct mtk_mdp_dev - abstraction for image processor entity
  * @lock:	the mutex protecting this data structure
  * @vpulock:	the mutex protecting the communication with VPU
+ * @use_components: use sibling component PM supplier links
  * @pdev:	pointer to the image processor platform device
  * @variant:	the IP variant information
  * @id:		image processor device index (0..MTK_MDP_MAX_DEVS)
@@ -152,6 +153,7 @@ struct mtk_mdp_dev {
 	struct mutex			lock;
 	struct mutex			vpulock;
 	struct platform_device		*pdev;
+	bool				use_components;
 	struct mtk_mdp_variant		*variant;
 	u16				id;
 	struct list_head		comp_list;
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
new file mode 100644
index 0000000..a984f23
--- /dev/null
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Keep the DMA component suppliers powered for the master runtime lifetime. */
+#include <linux/component.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+struct mtk_mdp_pm_component {
+	struct device_link *link;
+};
+
+static int mtk_mdp_pm_bind(struct device *dev, struct device *master, void *data)
+{
+	struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+	/* The component already has its IOMMU/LARB runtime-PM supplier link. */
+	comp->link = device_link_add(master, dev,
+				     DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+	return comp->link ? 0 : -ENOMEM;
+}
+
+static void mtk_mdp_pm_unbind(struct device *dev, struct device *master,
+			      void *data)
+{
+	struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+	device_link_del(comp->link);
+	comp->link = NULL;
+}
+
+static const struct component_ops mtk_mdp_pm_component_ops = {
+	.bind = mtk_mdp_pm_bind,
+	.unbind = mtk_mdp_pm_unbind,
+};
+
+static int mtk_mdp_pm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mtk_mdp_pm_component *comp;
+	int ret;
+
+	/* RDMA0 is the master; it must not become its own supplier. */
+	if (of_property_present(dev->of_node, "mediatek,vpu"))
+		return -ENODEV;
+	comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
+	if (!comp)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, comp);
+	pm_runtime_enable(dev);
+	ret = component_add(dev, &mtk_mdp_pm_component_ops);
+	if (ret)
+		pm_runtime_disable(dev);
+	return ret;
+}
+
+static void mtk_mdp_pm_remove(struct platform_device *pdev)
+{
+	component_del(&pdev->dev, &mtk_mdp_pm_component_ops);
+	pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id mtk_mdp_pm_of_match[] = {
+	{ .compatible = "mediatek,mt8173-mdp-rdma" },
+	{ .compatible = "mediatek,mt8173-mdp-rsz" },
+	{ .compatible = "mediatek,mt8173-mdp-wdma" },
+	{ .compatible = "mediatek,mt8173-mdp-wrot" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mtk_mdp_pm_of_match);
+
+struct platform_driver mtk_mdp_pm_component_driver = {
+	.probe = mtk_mdp_pm_probe,
+	.remove = mtk_mdp_pm_remove,
+	.driver = {
+		.name = "mtk-mdp-pm-component",
+		.of_match_table = mtk_mdp_pm_of_match,
+	},
+};

---
base-commit: bf6c63ecc20a54aaac7a2fcbd6adaf6498388825
change-id: 20261111-rfc-v2-generated-dd4e5cfe8b3b

Best regards,
--  
Youngjoon Lee <getfeus@gmail.com>

回复: [RFC PATCH] media: mediatek: mdp: Keep component suppliers powered while streaming

[Xiandong Wang (王先冬)]

Dear getfeus:

I reviewed the patch and suggest adding two checks in mtk_mdp_probe():
1. Check IS_ERR(match) immediately after each component_match_add_release() call. This function returns void and reports allocation failures through the match pointer. On failure, propagate PTR_ERR(match), release both the unconsumed OF-node reference and the loop reference, then jump to the existing err_comp cleanup label.
2. Check for an empty match list after the sibling-node loop. When mdp->use_components is true but no matching sibling components are found, match remains NULL. Return -ENODEV through err_comp before calling component_master_add_with_match(), which expects a valid match list.

like as bellow:

diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
index 372b485d1d4d..3876bb7a68f3 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
@@ -204,11 +204,26 @@
 		}
 
 		mtk_mdp_register_component(mdp, comp);
+		if (mdp->use_components && node != dev->of_node) {
+			struct device_node *match_node = of_node_get(node);
+
 			component_match_add_release(dev, &match,
 						    mtk_mdp_release_component,
 						    mtk_mdp_compare_component,
-						    of_node_get(node));
+						    match_node);
+			if (IS_ERR(match)) {
+				ret = PTR_ERR(match);
+				/* The failed entry did not consume this reference. */
+				of_node_put(match_node);
+				of_node_put(node);
+				goto err_comp;
+			}
+		}
+	}
+
+	if (mdp->use_components && !match) {
+		ret = -ENODEV;
+		goto err_comp;
 	}

Please check it and test.

Best regards,

-----邮件原件-----
发件人: getfeus@gmail.com <getfeus@gmail.com> 
发送时间: 2026年11月11日 11:39
收件人: Minghsiu Tsai (蔡明修) <Minghsiu.Tsai@mediatek.com>; Houlong Wei (魏厚龙) <houlong.wei@mediatek.com>; Andrew-CT Chen (陳智迪) <Andrew-CT.Chen@mediatek.com>; mchehab@kernel.org
抄送: linux-media@vger.kernel.org; linux-mediatek@lists.infradead.org
主题: [RFC PATCH] media: mediatek: mdp: Keep component suppliers powered while streaming


External email : Please do not click links or open attachments until you have verified the sender or the content.


Hi,

Following up on my earlier report ("MT8173 legacy MDP: PROCESS_ACK status 0 but CAPTURE remains unchanged"), I dug into the runtime-PM dependencies on an MT8173 Elm Chromebook.

The legacy MDP driver manages the clocks for its sibling blocks directly from the RDMA0 master, but it does not establish runtime-PM dependencies from the master to those devices. As a result, their suppliers are not all kept active during processing. In particular,
LARB4 stays suspended.

In the failing case, the firmware reports success and both buffers complete, yet the CAPTURE planes remain untouched, matching the pre-queue canary. Keeping LARB4 active before the first job changes the output to a byte-exact copy.

The proposed fix binds the sibling blocks as components and adds runtime-PM device links from the master to them. Their existing IOMMU/LARB supplier links then propagate the required PM references.
Engine clock handling stays in the master, and the M2M device is registered only after all required components have bound. The existing fallback path for legacy child-node DTs is retained.

I also reproduced an IOMMU read fault on LARB4 port 4 (MDP_RDMA1) after closing a failed job and unmapping its buffers. Tracing associated the reported fault page with that job's input Y allocation.
No second PROCESS command was submitted before the fault was reported during the subsequent LARB4 reactivation sequence.

The patch fixes the missing PM dependencies. All ten conversion tests passed with pixel-exact output and no IOMMU faults, without manually forcing LARB4 on.

Tested on Elm (next-20261105-based kernel, VPU firmware v1.2.0):

- Seven NV12M 640x360 copy jobs produced byte-exact Y/UV output.
- Three saved MT21C 640x384 to YUV420M 640x360 conversions matched the software-decoded reference across all visible Y/U/V samples.
- Testing covered both temporary module loading and loading the candidate during boot.
- LARB4 remained under the "auto" PM policy, became active during streaming, and suspended again after streaming stopped.
- Three STREAMON-without-buffers checks returned the expected EINVAL, with no additional PROCESS commands or observed PM cleanup failures.
- The PM changes apply and build cleanly against next-20261105 without the diagnostic instrumentation.

The diff below is based on current linux-next (793807ca13bf). Compared with the tested next-20261105 files, the only intervening changes in these files are two devm_kzalloc_obj() substitutions. Those upstream changes are retained; the proposed PM changes are unchanged.

System suspend/resume, other boards, legacy child-node DTs, and probe/allocation error-injection paths have not been tested.

Does this look like the right way to model the runtime-PM dependencies for the legacy MDP components? I'd especially appreciate feedback on the device-link lifetime and component bind/unbind ordering.

I have the userspace reproducer, deterministic test pattern generator, and ftrace logs available if useful.

Thanks,
Youngjoon Lee

Signed-off-by: Youngjoon Lee <getfeus@gmail.com>
---
 drivers/media/platform/mediatek/mdp/Makefile       |  1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h |  1 +  drivers/media/platform/mediatek/mdp/mtk_mdp_core.c | 91 +++++++++++++++++++---  drivers/media/platform/mediatek/mdp/mtk_mdp_core.h |  2 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c   | 81 +++++++++++++++++++
 5 files changed, 165 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/mediatek/mdp/Makefile
b/drivers/media/platform/mediatek/mdp/Makefile
index b7c16eb..c3f3a74 100644
--- a/drivers/media/platform/mediatek/mdp/Makefile
+++ b/drivers/media/platform/mediatek/mdp/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 mtk-mdp-y += mtk_mdp_core.o
+mtk-mdp-y += mtk_mdp_pm.o
 mtk-mdp-y += mtk_mdp_comp.o
 mtk-mdp-y += mtk_mdp_m2m.o
 mtk-mdp-y += mtk_mdp_regs.o
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
index ae41dd3..c9098d8 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
@@ -42,5 +42,6 @@ void mtk_mdp_comp_deinit(struct device *dev, struct mtk_mdp_comp *comp);  void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp);  void mtk_mdp_comp_clock_off(struct device *dev, struct mtk_mdp_comp *comp);

+extern struct platform_driver mtk_mdp_pm_component_driver;

 #endif /* __MTK_MDP_COMP_H__ */
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
index c065cde..23bcaa8 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
@@ -6,6 +6,7 @@
  */

 #include <linux/clk.h>
+#include <linux/component.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
@@ -102,12 +103,50 @@ void mtk_mdp_unregister_component(struct mtk_mdp_dev *mdp,
        list_del(&comp->node);
 }

+static int mtk_mdp_compare_component(struct device *dev, void *data) {
+       return dev->of_node == data;
+}
+
+static void mtk_mdp_release_component(struct device *dev, void *data) {
+       of_node_put(data);
+}
+
+static int mtk_mdp_master_bind(struct device *dev) {
+       struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+       int ret;
+
+       ret = component_bind_all(dev, mdp);
+       if (ret)
+               return ret;
+       ret = mtk_mdp_register_m2m_device(mdp);
+       if (ret)
+               component_unbind_all(dev, mdp);
+       return ret;
+}
+
+static void mtk_mdp_master_unbind(struct device *dev) {
+       struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+
+       mtk_mdp_unregister_m2m_device(mdp);
+       component_unbind_all(dev, mdp);
+}
+
+static const struct component_master_ops mtk_mdp_master_ops = {
+       .bind = mtk_mdp_master_bind,
+       .unbind = mtk_mdp_master_unbind, };
+
 static int mtk_mdp_probe(struct platform_device *pdev)  {
        struct mtk_mdp_dev *mdp;
        struct device *dev = &pdev->dev;
        struct device_node *node, *parent;
        struct mtk_mdp_comp *comp, *comp_temp;
+       struct component_match *match = NULL;
        int ret = 0;

        mdp = devm_kzalloc_obj(dev, *mdp); @@ -132,6 +171,8 @@ static int mtk_mdp_probe(struct platform_device *pdev)
                parent = dev->of_node->parent;
        }

+       mdp->use_components = parent != dev->of_node;
+
        /* Iterate over sibling MDP function blocks */
        for_each_child_of_node(parent, node) {
                const struct of_device_id *of_id; @@ -163,6 +204,11 @@ static int mtk_mdp_probe(struct platform_device *pdev)
                }

                mtk_mdp_register_component(mdp, comp);
+               if (mdp->use_components && node != dev->of_node)
+                       component_match_add_release(dev, &match,
+                                                   mtk_mdp_release_component,
+                                                   mtk_mdp_compare_component,
+                                                   of_node_get(node));
        }

        mdp->job_wq = create_singlethread_workqueue(MTK_MDP_MODULE_NAME);
@@ -187,12 +233,6 @@ static int mtk_mdp_probe(struct platform_device *pdev)
                goto err_dev_register;
        }

-       ret = mtk_mdp_register_m2m_device(mdp);
-       if (ret) {
-               v4l2_err(&mdp->v4l2_dev, "Failed to init mem2mem device\n");
-               goto err_m2m_register;
-       }
-
        mdp->vpu_dev = vpu_get_plat_device(pdev);
        if (!mdp->vpu_dev) {
                dev_err(&pdev->dev, "Failed to get vpu device\n"); @@ -216,17 +256,25 @@ static int mtk_mdp_probe(struct platform_device *pdev)
        }

        pm_runtime_enable(dev);
+       if (mdp->use_components)
+               ret = component_master_add_with_match(dev, &mtk_mdp_master_ops,
+                                                     match);
+       else
+               ret = mtk_mdp_register_m2m_device(mdp);
+       if (ret)
+               goto err_register_components;
        dev_dbg(dev, "mdp-%d registered successfully\n", mdp->id);

        return 0;

+err_register_components:
+       pm_runtime_disable(dev);
+       vb2_dma_contig_clear_max_seg_size(dev);
+
 err_reg_handler:
        platform_device_put(mdp->vpu_dev);

 err_vpu_get_dev:
-       mtk_mdp_unregister_m2m_device(mdp);
-
-err_m2m_register:
        v4l2_device_unregister(&mdp->v4l2_dev);

 err_dev_register:
@@ -252,10 +300,13 @@ static void mtk_mdp_remove(struct platform_device *pdev)
        struct mtk_mdp_dev *mdp = platform_get_drvdata(pdev);
        struct mtk_mdp_comp *comp, *comp_temp;

+       if (mdp->use_components)
+               component_master_del(&pdev->dev, &mtk_mdp_master_ops);
+       else
+               mtk_mdp_unregister_m2m_device(mdp);
        pm_runtime_disable(&pdev->dev);
        vb2_dma_contig_clear_max_seg_size(&pdev->dev);
        platform_device_put(mdp->vpu_dev);
-       mtk_mdp_unregister_m2m_device(mdp);
        v4l2_device_unregister(&mdp->v4l2_dev);

        destroy_workqueue(mdp->wdt_wq);
@@ -319,7 +370,25 @@ static struct platform_driver mtk_mdp_driver = {
        }
 };

-module_platform_driver(mtk_mdp_driver);
+static struct platform_driver * const mtk_mdp_drivers[] = {
+       &mtk_mdp_pm_component_driver,
+       &mtk_mdp_driver,
+};
+
+static int __init mtk_mdp_init(void)
+{
+       return platform_register_drivers(mtk_mdp_drivers,
+                                        ARRAY_SIZE(mtk_mdp_drivers)); }
+
+static void __exit mtk_mdp_exit(void)
+{
+       platform_unregister_drivers(mtk_mdp_drivers,
+                                   ARRAY_SIZE(mtk_mdp_drivers)); }
+
+module_init(mtk_mdp_init);
+module_exit(mtk_mdp_exit);

 MODULE_AUTHOR("Houlong Wei <houlong.wei@mediatek.com>");  MODULE_DESCRIPTION("Mediatek image processor driver"); diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
index a6e6dc3..c9004e4 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
@@ -133,6 +133,7 @@ struct mtk_mdp_variant {
  * struct mtk_mdp_dev - abstraction for image processor entity
  * @lock:      the mutex protecting this data structure
  * @vpulock:   the mutex protecting the communication with VPU
+ * @use_components: use sibling component PM supplier links
  * @pdev:      pointer to the image processor platform device
  * @variant:   the IP variant information
  * @id:                image processor device index (0..MTK_MDP_MAX_DEVS)
@@ -152,6 +153,7 @@ struct mtk_mdp_dev {
        struct mutex                    lock;
        struct mutex                    vpulock;
        struct platform_device          *pdev;
+       bool                            use_components;
        struct mtk_mdp_variant          *variant;
        u16                             id;
        struct list_head                comp_list;
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
new file mode 100644
index 0000000..a984f23
--- /dev/null
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Keep the DMA component suppliers powered for the master runtime 
+lifetime. */ #include <linux/component.h> #include <linux/device.h> 
+#include <linux/module.h> #include <linux/of.h> #include 
+<linux/platform_device.h> #include <linux/pm_runtime.h> #include 
+<linux/slab.h>
+
+struct mtk_mdp_pm_component {
+       struct device_link *link;
+};
+
+static int mtk_mdp_pm_bind(struct device *dev, struct device *master,
void *data)
+{
+       struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+       /* The component already has its IOMMU/LARB runtime-PM supplier link. */
+       comp->link = device_link_add(master, dev,
+                                    DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+       return comp->link ? 0 : -ENOMEM; }
+
+static void mtk_mdp_pm_unbind(struct device *dev, struct device *master,
+                             void *data) {
+       struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+       device_link_del(comp->link);
+       comp->link = NULL;
+}
+
+static const struct component_ops mtk_mdp_pm_component_ops = {
+       .bind = mtk_mdp_pm_bind,
+       .unbind = mtk_mdp_pm_unbind,
+};
+
+static int mtk_mdp_pm_probe(struct platform_device *pdev) {
+       struct device *dev = &pdev->dev;
+       struct mtk_mdp_pm_component *comp;
+       int ret;
+
+       /* RDMA0 is the master; it must not become its own supplier. */
+       if (of_property_present(dev->of_node, "mediatek,vpu"))
+               return -ENODEV;
+       comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
+       if (!comp)
+               return -ENOMEM;
+       platform_set_drvdata(pdev, comp);
+       pm_runtime_enable(dev);
+       ret = component_add(dev, &mtk_mdp_pm_component_ops);
+       if (ret)
+               pm_runtime_disable(dev);
+       return ret;
+}
+
+static void mtk_mdp_pm_remove(struct platform_device *pdev) {
+       component_del(&pdev->dev, &mtk_mdp_pm_component_ops);
+       pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id mtk_mdp_pm_of_match[] = {
+       { .compatible = "mediatek,mt8173-mdp-rdma" },
+       { .compatible = "mediatek,mt8173-mdp-rsz" },
+       { .compatible = "mediatek,mt8173-mdp-wdma" },
+       { .compatible = "mediatek,mt8173-mdp-wrot" },
+       { }
+};
+MODULE_DEVICE_TABLE(of, mtk_mdp_pm_of_match);
+
+struct platform_driver mtk_mdp_pm_component_driver = {
+       .probe = mtk_mdp_pm_probe,
+       .remove = mtk_mdp_pm_remove,
+       .driver = {
+               .name = "mtk-mdp-pm-component",
+               .of_match_table = mtk_mdp_pm_of_match,
+       },
+};

[PATCH RFC v3] media: mediatek: mdp: Keep component suppliers powered while streaming

[Youngjoon Lee via B4 Relay]

From: Youngjoon Lee <getfeus@gmail.com>

Sibling clocks are enabled without keeping their PM suppliers active.

On MT8173 Elm, LARB4 stays suspended and CAPTURE memory is unchanged.
The firmware reports success despite the unchanged CAPTURE buffers.

Bind sibling blocks and add runtime-PM links from the RDMA0 master.
Retain master clock handling and the legacy child-node DT fallback.

Handle match allocation errors before registering the master.
Release the unconsumed node reference and reject empty match lists.

Suggested-by: Xiandong Wang <Xiandong.Wang@mediatek.com>
Signed-off-by: Youngjoon Lee <getfeus@gmail.com>
---
Hi Xiandong,

Thanks for catching both error paths. I added the IS_ERR(match) check immediately after each component_match_add_release() call, release the unconsumed match-node reference and the loop reference on failure, and propagate PTR_ERR(match) through err_comp. I also reject an empty sibling match list with -ENODEV before creating the workqueues or registering the master.

I tested the revised code on Elm. A separate test-only module injected ERR_PTR(-ENOMEM) at each of the seven sibling match-add call positions. All seven cases returned -ENOMEM, cleaned every registered component, and restored the actual kref counts of all eight MDP OF nodes to their pre-probe values. The framework released the previously accepted match entries; the failed entry and loop references were released by the new error path.

Two more probe tests omitted the sibling matches, and then all matching blocks. Both returned -ENODEV before master registration and left no M2M node. The same eight OF-node reference counts were unchanged after cleanup.

These were deterministic API-boundary error-pointer injections in an isolated test module. CONFIG_FAULT_INJECTION is disabled in this kernel, so they were not failslab or real system-wide OOM tests. None of the injection hooks are in the submitted patch.

Normal regression with the revised diagnostic module also passed: three NV12M 640x360 copies were byte-exact, one saved MT21C 640x384 to YUV420M 640x360 conversion matched every visible software-reference Y/U/V sample, and one STREAMON-without-buffers check returned the expected EINVAL. No IOMMU faults were observed. LARB4 remained on auto, woke during streaming, and suspended afterward.

Clean and diagnostic module builds passed without compiler warnings or errors. The review-only incremental patch passed strict checkpatch. System suspend/resume, other boards and real legacy child-node DT hardware remain untested.

Changes in v3:
- Handle component-match allocation errors and release both outstanding node references.
- Reject an empty match list when sibling components are required.
- Add Suggested-by credit for Xiandong Wang.
- Test all seven match-add failure positions, two empty-list cases, and the normal conversion path.

The runtime-PM supplier-link approach and engine clock ownership are otherwise unchanged. I used the media next baseline (bf6c63ecc20a), as in v2.

Thanks,
Youngjoon Lee
---
 drivers/media/platform/mediatek/mdp/Makefile       |   1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h |   1 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_core.c | 106 ++++++++++++++++++---
 drivers/media/platform/mediatek/mdp/mtk_mdp_core.h |   2 +
 drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c   |  81 ++++++++++++++++
 5 files changed, 180 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/mediatek/mdp/Makefile b/drivers/media/platform/mediatek/mdp/Makefile
index b7c16eb..c3f3a74 100644
--- a/drivers/media/platform/mediatek/mdp/Makefile
+++ b/drivers/media/platform/mediatek/mdp/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 mtk-mdp-y += mtk_mdp_core.o
+mtk-mdp-y += mtk_mdp_pm.o
 mtk-mdp-y += mtk_mdp_comp.o
 mtk-mdp-y += mtk_mdp_m2m.o
 mtk-mdp-y += mtk_mdp_regs.o
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
index ae41dd3..c9098d8 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_comp.h
@@ -42,5 +42,6 @@ void mtk_mdp_comp_deinit(struct device *dev, struct mtk_mdp_comp *comp);
 void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp);
 void mtk_mdp_comp_clock_off(struct device *dev, struct mtk_mdp_comp *comp);
 
+extern struct platform_driver mtk_mdp_pm_component_driver;
 
 #endif /* __MTK_MDP_COMP_H__ */
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
index 8432833..8a8632d 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/component.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
@@ -102,12 +103,50 @@ void mtk_mdp_unregister_component(struct mtk_mdp_dev *mdp,
 	list_del(&comp->node);
 }
 
+static int mtk_mdp_compare_component(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
+
+static void mtk_mdp_release_component(struct device *dev, void *data)
+{
+	of_node_put(data);
+}
+
+static int mtk_mdp_master_bind(struct device *dev)
+{
+	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+	int ret;
+
+	ret = component_bind_all(dev, mdp);
+	if (ret)
+		return ret;
+	ret = mtk_mdp_register_m2m_device(mdp);
+	if (ret)
+		component_unbind_all(dev, mdp);
+	return ret;
+}
+
+static void mtk_mdp_master_unbind(struct device *dev)
+{
+	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
+
+	mtk_mdp_unregister_m2m_device(mdp);
+	component_unbind_all(dev, mdp);
+}
+
+static const struct component_master_ops mtk_mdp_master_ops = {
+	.bind = mtk_mdp_master_bind,
+	.unbind = mtk_mdp_master_unbind,
+};
+
 static int mtk_mdp_probe(struct platform_device *pdev)
 {
 	struct mtk_mdp_dev *mdp;
 	struct device *dev = &pdev->dev;
 	struct device_node *node, *parent;
 	struct mtk_mdp_comp *comp, *comp_temp;
+	struct component_match *match = NULL;
 	int ret = 0;
 
 	mdp = devm_kzalloc(dev, sizeof(*mdp), GFP_KERNEL);
@@ -132,6 +171,8 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		parent = dev->of_node->parent;
 	}
 
+	mdp->use_components = parent != dev->of_node;
+
 	/* Iterate over sibling MDP function blocks */
 	for_each_child_of_node(parent, node) {
 		const struct of_device_id *of_id;
@@ -163,6 +204,26 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		}
 
 		mtk_mdp_register_component(mdp, comp);
+		if (mdp->use_components && node != dev->of_node) {
+			struct device_node *match_node = of_node_get(node);
+
+			component_match_add_release(dev, &match,
+						    mtk_mdp_release_component,
+						    mtk_mdp_compare_component,
+						    match_node);
+			if (IS_ERR(match)) {
+				ret = PTR_ERR(match);
+				/* The failed entry did not consume this reference. */
+				of_node_put(match_node);
+				of_node_put(node);
+				goto err_comp;
+			}
+		}
+	}
+
+	if (mdp->use_components && !match) {
+		ret = -ENODEV;
+		goto err_comp;
 	}
 
 	mdp->job_wq = create_singlethread_workqueue(MTK_MDP_MODULE_NAME);
@@ -187,12 +248,6 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 		goto err_dev_register;
 	}
 
-	ret = mtk_mdp_register_m2m_device(mdp);
-	if (ret) {
-		v4l2_err(&mdp->v4l2_dev, "Failed to init mem2mem device\n");
-		goto err_m2m_register;
-	}
-
 	mdp->vpu_dev = vpu_get_plat_device(pdev);
 	if (!mdp->vpu_dev) {
 		dev_err(&pdev->dev, "Failed to get vpu device\n");
@@ -216,17 +271,25 @@ static int mtk_mdp_probe(struct platform_device *pdev)
 	}
 
 	pm_runtime_enable(dev);
+	if (mdp->use_components)
+		ret = component_master_add_with_match(dev, &mtk_mdp_master_ops,
+						      match);
+	else
+		ret = mtk_mdp_register_m2m_device(mdp);
+	if (ret)
+		goto err_register_components;
 	dev_dbg(dev, "mdp-%d registered successfully\n", mdp->id);
 
 	return 0;
 
+err_register_components:
+	pm_runtime_disable(dev);
+	vb2_dma_contig_clear_max_seg_size(dev);
+
 err_reg_handler:
 	platform_device_put(mdp->vpu_dev);
 
 err_vpu_get_dev:
-	mtk_mdp_unregister_m2m_device(mdp);
-
-err_m2m_register:
 	v4l2_device_unregister(&mdp->v4l2_dev);
 
 err_dev_register:
@@ -252,10 +315,13 @@ static void mtk_mdp_remove(struct platform_device *pdev)
 	struct mtk_mdp_dev *mdp = platform_get_drvdata(pdev);
 	struct mtk_mdp_comp *comp, *comp_temp;
 
+	if (mdp->use_components)
+		component_master_del(&pdev->dev, &mtk_mdp_master_ops);
+	else
+		mtk_mdp_unregister_m2m_device(mdp);
 	pm_runtime_disable(&pdev->dev);
 	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 	platform_device_put(mdp->vpu_dev);
-	mtk_mdp_unregister_m2m_device(mdp);
 	v4l2_device_unregister(&mdp->v4l2_dev);
 
 	destroy_workqueue(mdp->wdt_wq);
@@ -319,7 +385,25 @@ static struct platform_driver mtk_mdp_driver = {
 	}
 };
 
-module_platform_driver(mtk_mdp_driver);
+static struct platform_driver * const mtk_mdp_drivers[] = {
+	&mtk_mdp_pm_component_driver,
+	&mtk_mdp_driver,
+};
+
+static int __init mtk_mdp_init(void)
+{
+	return platform_register_drivers(mtk_mdp_drivers,
+					 ARRAY_SIZE(mtk_mdp_drivers));
+}
+
+static void __exit mtk_mdp_exit(void)
+{
+	platform_unregister_drivers(mtk_mdp_drivers,
+				    ARRAY_SIZE(mtk_mdp_drivers));
+}
+
+module_init(mtk_mdp_init);
+module_exit(mtk_mdp_exit);
 
 MODULE_AUTHOR("Houlong Wei <houlong.wei@mediatek.com>");
 MODULE_DESCRIPTION("Mediatek image processor driver");
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
index a6e6dc3..c9004e4 100644
--- a/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_core.h
@@ -133,6 +133,7 @@ struct mtk_mdp_variant {
  * struct mtk_mdp_dev - abstraction for image processor entity
  * @lock:	the mutex protecting this data structure
  * @vpulock:	the mutex protecting the communication with VPU
+ * @use_components: use sibling component PM supplier links
  * @pdev:	pointer to the image processor platform device
  * @variant:	the IP variant information
  * @id:		image processor device index (0..MTK_MDP_MAX_DEVS)
@@ -152,6 +153,7 @@ struct mtk_mdp_dev {
 	struct mutex			lock;
 	struct mutex			vpulock;
 	struct platform_device		*pdev;
+	bool				use_components;
 	struct mtk_mdp_variant		*variant;
 	u16				id;
 	struct list_head		comp_list;
diff --git a/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
new file mode 100644
index 0000000..a984f23
--- /dev/null
+++ b/drivers/media/platform/mediatek/mdp/mtk_mdp_pm.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Keep the DMA component suppliers powered for the master runtime lifetime. */
+#include <linux/component.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+struct mtk_mdp_pm_component {
+	struct device_link *link;
+};
+
+static int mtk_mdp_pm_bind(struct device *dev, struct device *master, void *data)
+{
+	struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+	/* The component already has its IOMMU/LARB runtime-PM supplier link. */
+	comp->link = device_link_add(master, dev,
+				     DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+	return comp->link ? 0 : -ENOMEM;
+}
+
+static void mtk_mdp_pm_unbind(struct device *dev, struct device *master,
+			      void *data)
+{
+	struct mtk_mdp_pm_component *comp = dev_get_drvdata(dev);
+
+	device_link_del(comp->link);
+	comp->link = NULL;
+}
+
+static const struct component_ops mtk_mdp_pm_component_ops = {
+	.bind = mtk_mdp_pm_bind,
+	.unbind = mtk_mdp_pm_unbind,
+};
+
+static int mtk_mdp_pm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mtk_mdp_pm_component *comp;
+	int ret;
+
+	/* RDMA0 is the master; it must not become its own supplier. */
+	if (of_property_present(dev->of_node, "mediatek,vpu"))
+		return -ENODEV;
+	comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
+	if (!comp)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, comp);
+	pm_runtime_enable(dev);
+	ret = component_add(dev, &mtk_mdp_pm_component_ops);
+	if (ret)
+		pm_runtime_disable(dev);
+	return ret;
+}
+
+static void mtk_mdp_pm_remove(struct platform_device *pdev)
+{
+	component_del(&pdev->dev, &mtk_mdp_pm_component_ops);
+	pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id mtk_mdp_pm_of_match[] = {
+	{ .compatible = "mediatek,mt8173-mdp-rdma" },
+	{ .compatible = "mediatek,mt8173-mdp-rsz" },
+	{ .compatible = "mediatek,mt8173-mdp-wdma" },
+	{ .compatible = "mediatek,mt8173-mdp-wrot" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mtk_mdp_pm_of_match);
+
+struct platform_driver mtk_mdp_pm_component_driver = {
+	.probe = mtk_mdp_pm_probe,
+	.remove = mtk_mdp_pm_remove,
+	.driver = {
+		.name = "mtk-mdp-pm-component",
+		.of_match_table = mtk_mdp_pm_of_match,
+	},
+};

---
base-commit: bf6c63ecc20a54aaac7a2fcbd6adaf6498388825
change-id: 20261111-rfc-v2-generated-dd4e5cfe8b3b

Best regards,
--  
Youngjoon Lee <getfeus@gmail.com>