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

[Youngjoon Lee via B4 Relay <devnull+getfeus.gmail.com@kernel.org>]

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>