drm/mediatek: Implement OF graphs support for display paths

It is impossible to add each and every possible DDP path combination
for each and every possible combination of SoC and board: right now,
this driver hardcodes configuration for 10 SoCs and this is going to
grow larger and larger, and with new hacks like the introduction of
mtk_drm_route which is anyway not enough for all final routes as the
DSI cannot be connected to MERGE if it's not a dual-DSI, or enabling
DSC preventively doesn't work if the display doesn't support it, or
others.

Since practically all display IPs in MediaTek SoCs support being
interconnected with different instances of other, or the same, IPs
or with different IPs and in different combinations, the final DDP
pipeline is effectively a board specific configuration.

Implement OF graphs support to the mediatek-drm drivers, allowing to
stop hardcoding the paths, and preventing this driver to get a huge
amount of arrays for each board and SoC combination, also paving the
way to share the same mtk_mmsys_driver_data between multiple SoCs,
making it more straightforward to add support for new chips.

Note that the OVL_ADAPTOR software component driver needs relatively
big changes in order to fully support OF Graphs (and more SoCs anyway)
and such changes will come at a later time.
As of now, the mtk_disp_ovl_adaptor driver takes the MERGE components
(for example, on mt8195, merge 1 to 4) dynamically so, even though
later updates to the ovl-adaptor driver will *not* require bindings
changes, the merge1-4 will be temporarily omitted in the graph for the
MT8195 SoC.

This means that an example graph for this SoC looks like:

mdp_rdma (0 ~ 7) -> padding (0 ~ 7) -> ethdr -> merge5

and the resulting path in this driver will be `ovl_adaptor -> merge5`

Later updates to the ovl adaptor will expand it to support more SoCs
and, in turn, to also fully support graphs.

Reviewed-by: Alexandre Mergnat <[e-mail]>
Tested-by: Alexandre Mergnat <[e-mail]>
Acked-by: Sui Jingfeng <[e-mail]>
Tested-by: Michael Walle <[e-mail]> # on kontron-sbc-i1200
Reviewed-by: CK Hu <[e-mail]>
Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>
Link: https://patchwork.kernel.org/project/dri-devel/patch/[e-mail]/
Signed-off-by: Chun-Kuang Hu <[e-mail]>

drivers/gpu/drm/mediatek/mtk_disp_drv.h

···
 
 void mtk_ovl_adaptor_add_comp(struct device *dev, struct mtk_mutex *mutex);
 void mtk_ovl_adaptor_remove_comp(struct device *dev, struct mtk_mutex *mutex);
+bool mtk_ovl_adaptor_is_comp_present(struct device_node *node);
 void mtk_ovl_adaptor_connect(struct device *dev, struct device *mmsys_dev,
 			     unsigned int next);
 void mtk_ovl_adaptor_disconnect(struct device *dev, struct device *mmsys_dev,

drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c

···
 	return dev->of_node == data;
 }
 
+static int ovl_adaptor_of_get_ddp_comp_type(struct device_node *node,
+					    enum mtk_ovl_adaptor_comp_type *ctype)
+{
+	const struct of_device_id *of_id = of_match_node(mtk_ovl_adaptor_comp_dt_ids, node);
+
+	if (!of_id)
+		return -EINVAL;
+
+	*ctype = (enum mtk_ovl_adaptor_comp_type)((uintptr_t)of_id->data);
+
+	return 0;
+}
+
+bool mtk_ovl_adaptor_is_comp_present(struct device_node *node)
+{
+	enum mtk_ovl_adaptor_comp_type type;
+	int ret;
+
+	ret = ovl_adaptor_of_get_ddp_comp_type(node, &type);
+	if (ret)
+		return false;
+
+	if (type >= OVL_ADAPTOR_TYPE_NUM)
+		return false;
+
+	/*
+	 * In the context of mediatek-drm, ETHDR, MDP_RDMA and Padding are
+	 * used exclusively by OVL Adaptor: if this component is not one of
+	 * those, it's likely not an OVL Adaptor path.
+	 */
+	return type == OVL_ADAPTOR_TYPE_ETHDR ||
+	       type == OVL_ADAPTOR_TYPE_MDP_RDMA ||
+	       type == OVL_ADAPTOR_TYPE_PADDING;
+}
+
 static int ovl_adaptor_comp_init(struct device *dev, struct component_match **match)
 {
 	struct mtk_disp_ovl_adaptor *priv = dev_get_drvdata(dev);
···
 	parent = dev->parent->parent->of_node->parent;
 
 	for_each_child_of_node_scoped(parent, node) {
-		const struct of_device_id *of_id;
 		enum mtk_ovl_adaptor_comp_type type;
-		int id;
+		int id, ret;
 
-		of_id = of_match_node(mtk_ovl_adaptor_comp_dt_ids, node);
-		if (!of_id)
+		ret = ovl_adaptor_of_get_ddp_comp_type(node, &type);
+		if (ret)
 			continue;
 
 		if (!of_device_is_available(node)) {
···
 			continue;
 		}
 
-		type = (enum mtk_ovl_adaptor_comp_type)(uintptr_t)of_id->data;
 		id = ovl_adaptor_comp_get_id(dev, node, type);
 		if (id < 0) {
 			dev_warn(dev, "Skipping unknown component %pOF\n",

drivers/gpu/drm/mediatek/mtk_dpi.c

···
 				 enum drm_bridge_attach_flags flags)
 {
 	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
+	int ret;
+
+	dpi->next_bridge = devm_drm_of_get_bridge(dpi->dev, dpi->dev->of_node, 1, -1);
+	if (IS_ERR(dpi->next_bridge)) {
+		ret = PTR_ERR(dpi->next_bridge);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		/* Old devicetree has only one endpoint */
+		dpi->next_bridge = devm_drm_of_get_bridge(dpi->dev, dpi->dev->of_node, 0, 0);
+		if (IS_ERR(dpi->next_bridge))
+			return dev_err_probe(dpi->dev, PTR_ERR(dpi->next_bridge),
+					     "Failed to get bridge\n");
+	}
 
 	return drm_bridge_attach(bridge->encoder, dpi->next_bridge,
 				 &dpi->bridge, flags);
···
 	dpi->irq = platform_get_irq(pdev, 0);
 	if (dpi->irq < 0)
 		return dpi->irq;
-
-	dpi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
-	if (IS_ERR(dpi->next_bridge))
-		return dev_err_probe(dev, PTR_ERR(dpi->next_bridge),
-				     "Failed to get bridge\n");
-
-	dev_info(dev, "Found bridge node: %pOF\n", dpi->next_bridge->of_node);
 
 	platform_set_drvdata(pdev, dpi);
 

drivers/gpu/drm/mediatek/mtk_drm_drv.c

···
 
 #include "mtk_crtc.h"
 #include "mtk_ddp_comp.h"
+#include "mtk_disp_drv.h"
 #include "mtk_drm_drv.h"
 #include "mtk_gem.h"
 
···
 	{ }
 };
 
+static int mtk_drm_of_get_ddp_comp_type(struct device_node *node, enum mtk_ddp_comp_type *ctype)
+{
+	const struct of_device_id *of_id = of_match_node(mtk_ddp_comp_dt_ids, node);
+
+	if (!of_id)
+		return -EINVAL;
+
+	*ctype = (enum mtk_ddp_comp_type)((uintptr_t)of_id->data);
+
+	return 0;
+}
+
+static int mtk_drm_of_get_ddp_ep_cid(struct device_node *node,
+				     int output_port, enum mtk_crtc_path crtc_path,
+				     struct device_node **next, unsigned int *cid)
+{
+	struct device_node *ep_dev_node, *ep_out;
+	enum mtk_ddp_comp_type comp_type;
+	int ret;
+
+	ep_out = of_graph_get_endpoint_by_regs(node, output_port, crtc_path);
+	if (!ep_out)
+		return -ENOENT;
+
+	ep_dev_node = of_graph_get_remote_port_parent(ep_out);
+	of_node_put(ep_out);
+	if (!ep_dev_node)
+		return -EINVAL;
+
+	/*
+	 * Pass the next node pointer regardless of failures in the later code
+	 * so that if this function is called in a loop it will walk through all
+	 * of the subsequent endpoints anyway.
+	 */
+	*next = ep_dev_node;
+
+	if (!of_device_is_available(ep_dev_node))
+		return -ENODEV;
+
+	ret = mtk_drm_of_get_ddp_comp_type(ep_dev_node, &comp_type);
+	if (ret) {
+		if (mtk_ovl_adaptor_is_comp_present(ep_dev_node)) {
+			*cid = (unsigned int)DDP_COMPONENT_DRM_OVL_ADAPTOR;
+			return 0;
+		}
+		return ret;
+	}
+
+	ret = mtk_ddp_comp_get_id(ep_dev_node, comp_type);
+	if (ret < 0)
+		return ret;
+
+	/* All ok! Pass the Component ID to the caller. */
+	*cid = (unsigned int)ret;
+
+	return 0;
+}
+
+/**
+ * mtk_drm_of_ddp_path_build_one - Build a Display HW Pipeline for a CRTC Path
+ * @dev:          The mediatek-drm device
+ * @cpath:        CRTC Path relative to a VDO or MMSYS
+ * @out_path:     Pointer to an array that will contain the new pipeline
+ * @out_path_len: Number of entries in the pipeline array
+ *
+ * MediaTek SoCs can use different DDP hardware pipelines (or paths) depending
+ * on the board-specific desired display configuration; this function walks
+ * through all of the output endpoints starting from a VDO or MMSYS hardware
+ * instance and builds the right pipeline as specified in device trees.
+ *
+ * Return:
+ * * %0       - Display HW Pipeline successfully built and validated
+ * * %-ENOENT - Display pipeline was not specified in device tree
+ * * %-EINVAL - Display pipeline built but validation failed
+ * * %-ENOMEM - Failure to allocate pipeline array to pass to the caller
+ */
+static int mtk_drm_of_ddp_path_build_one(struct device *dev, enum mtk_crtc_path cpath,
+					 const unsigned int **out_path,
+					 unsigned int *out_path_len)
+{
+	struct device_node *next, *prev, *vdo = dev->parent->of_node;
+	unsigned int temp_path[DDP_COMPONENT_DRM_ID_MAX] = { 0 };
+	unsigned int *final_ddp_path;
+	unsigned short int idx = 0;
+	bool ovl_adaptor_comp_added = false;
+	int ret;
+
+	/* Get the first entry for the temp_path array */
+	ret = mtk_drm_of_get_ddp_ep_cid(vdo, 0, cpath, &next, &temp_path[idx]);
+	if (ret) {
+		if (next && temp_path[idx] == DDP_COMPONENT_DRM_OVL_ADAPTOR) {
+			dev_dbg(dev, "Adding OVL Adaptor for %pOF\n", next);
+			ovl_adaptor_comp_added = true;
+		} else {
+			if (next)
+				dev_err(dev, "Invalid component %pOF\n", next);
+			else
+				dev_err(dev, "Cannot find first endpoint for path %d\n", cpath);
+
+			return ret;
+		}
+	}
+	idx++;
+
+	/*
+	 * Walk through port outputs until we reach the last valid mediatek-drm component.
+	 * To be valid, this must end with an "invalid" component that is a display node.
+	 */
+	do {
+		prev = next;
+		ret = mtk_drm_of_get_ddp_ep_cid(next, 1, cpath, &next, &temp_path[idx]);
+		of_node_put(prev);
+		if (ret) {
+			of_node_put(next);
+			break;
+		}
+
+		/*
+		 * If this is an OVL adaptor exclusive component and one of those
+		 * was already added, don't add another instance of the generic
+		 * DDP_COMPONENT_OVL_ADAPTOR, as this is used only to decide whether
+		 * to probe that component master driver of which only one instance
+		 * is needed and possible.
+		 */
+		if (temp_path[idx] == DDP_COMPONENT_DRM_OVL_ADAPTOR) {
+			if (!ovl_adaptor_comp_added)
+				ovl_adaptor_comp_added = true;
+			else
+				idx--;
+		}
+	} while (++idx < DDP_COMPONENT_DRM_ID_MAX);
+
+	/*
+	 * The device component might not be enabled: in that case, don't
+	 * check the last entry and just report that the device is missing.
+	 */
+	if (ret == -ENODEV)
+		return ret;
+
+	/* If the last entry is not a final display output, the configuration is wrong */
+	switch (temp_path[idx - 1]) {
+	case DDP_COMPONENT_DP_INTF0:
+	case DDP_COMPONENT_DP_INTF1:
+	case DDP_COMPONENT_DPI0:
+	case DDP_COMPONENT_DPI1:
+	case DDP_COMPONENT_DSI0:
+	case DDP_COMPONENT_DSI1:
+	case DDP_COMPONENT_DSI2:
+	case DDP_COMPONENT_DSI3:
+		break;
+	default:
+		dev_err(dev, "Invalid display hw pipeline. Last component: %d (ret=%d)\n",
+			temp_path[idx - 1], ret);
+		return -EINVAL;
+	}
+
+	final_ddp_path = devm_kmemdup(dev, temp_path, idx * sizeof(temp_path[0]), GFP_KERNEL);
+	if (!final_ddp_path)
+		return -ENOMEM;
+
+	dev_dbg(dev, "Display HW Pipeline built with %d components.\n", idx);
+
+	/* Pipeline built! */
+	*out_path = final_ddp_path;
+	*out_path_len = idx;
+
+	return 0;
+}
+
+static int mtk_drm_of_ddp_path_build(struct device *dev, struct device_node *node,
+				     struct mtk_mmsys_driver_data *data)
+{
+	struct device_node *ep_node;
+	struct of_endpoint of_ep;
+	bool output_present[MAX_CRTC] = { false };
+	int ret;
+
+	for_each_endpoint_of_node(node, ep_node) {
+		ret = of_graph_parse_endpoint(ep_node, &of_ep);
+		if (ret) {
+			dev_err_probe(dev, ret, "Cannot parse endpoint\n");
+			break;
+		}
+
+		if (of_ep.id >= MAX_CRTC) {
+			ret = dev_err_probe(dev, -EINVAL,
+					    "Invalid endpoint%u number\n", of_ep.port);
+			break;
+		}
+
+		output_present[of_ep.id] = true;
+	}
+
+	if (ret) {
+		of_node_put(ep_node);
+		return ret;
+	}
+
+	if (output_present[CRTC_MAIN]) {
+		ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_MAIN,
+						    &data->main_path, &data->main_len);
+		if (ret && ret != -ENODEV)
+			return ret;
+	}
+
+	if (output_present[CRTC_EXT]) {
+		ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_EXT,
+						    &data->ext_path, &data->ext_len);
+		if (ret && ret != -ENODEV)
+			return ret;
+	}
+
+	if (output_present[CRTC_THIRD]) {
+		ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_THIRD,
+						    &data->third_path, &data->third_len);
+		if (ret && ret != -ENODEV)
+			return ret;
+	}
+
+	return 0;
+}
+
 static int mtk_drm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *phandle = dev->parent->of_node;
 	const struct of_device_id *of_id;
 	struct mtk_drm_private *private;
+	struct mtk_mmsys_driver_data *mtk_drm_data;
 	struct device_node *node;
 	struct component_match *match = NULL;
 	struct platform_device *ovl_adaptor;
···
 	if (!of_id)
 		return -ENODEV;
 
-	private->data = of_id->data;
+	mtk_drm_data = (struct mtk_mmsys_driver_data *)of_id->data;
+	if (!mtk_drm_data)
+		return -EINVAL;
+
+	/* Try to build the display pipeline from devicetree graphs */
+	if (of_graph_is_present(phandle)) {
+		dev_dbg(dev, "Building display pipeline for MMSYS %u\n",
+			mtk_drm_data->mmsys_id);
+		private->data = devm_kmemdup(dev, mtk_drm_data,
+					     sizeof(*mtk_drm_data), GFP_KERNEL);
+		if (!private->data)
+			return -ENOMEM;
+
+		ret = mtk_drm_of_ddp_path_build(dev, phandle, private->data);
+		if (ret)
+			return ret;
+	} else {
+		/* No devicetree graphs support: go with hardcoded paths if present */
+		dev_dbg(dev, "Using hardcoded paths for MMSYS %u\n", mtk_drm_data->mmsys_id);
+		private->data = mtk_drm_data;
+	};
 
 	private->all_drm_private = devm_kmalloc_array(dev, private->data->mmsys_dev_num,
 						      sizeof(*private->all_drm_private),
···
 
 	/* Iterate over sibling DISP function blocks */
 	for_each_child_of_node(phandle->parent, node) {
-		const struct of_device_id *of_id;
 		enum mtk_ddp_comp_type comp_type;
 		int comp_id;
 
-		of_id = of_match_node(mtk_ddp_comp_dt_ids, node);
-		if (!of_id)
+		ret = mtk_drm_of_get_ddp_comp_type(node, &comp_type);
+		if (ret)
 			continue;
 
 		if (!of_device_is_available(node)) {
···
 				node);
 			continue;
 		}
-
-		comp_type = (enum mtk_ddp_comp_type)(uintptr_t)of_id->data;
 
 		if (comp_type == MTK_DISP_MUTEX) {
 			int id;

drivers/gpu/drm/mediatek/mtk_drm_drv.h

···
 	struct device *mmsys_dev;
 	struct device_node *comp_node[DDP_COMPONENT_DRM_ID_MAX];
 	struct mtk_ddp_comp ddp_comp[DDP_COMPONENT_DRM_ID_MAX];
-	const struct mtk_mmsys_driver_data *data;
+	struct mtk_mmsys_driver_data *data;
 	struct drm_atomic_state *suspend_state;
 	unsigned int mbox_index;
 	struct mtk_drm_private **all_drm_private;

drivers/gpu/drm/mediatek/mtk_dsi.c

···
 	dsi->lanes = device->lanes;
 	dsi->format = device->format;
 	dsi->mode_flags = device->mode_flags;
-	dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
-	if (IS_ERR(dsi->next_bridge))
-		return PTR_ERR(dsi->next_bridge);
+	dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
+	if (IS_ERR(dsi->next_bridge)) {
+		ret = PTR_ERR(dsi->next_bridge);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		/* Old devicetree has only one endpoint */
+		dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
+		if (IS_ERR(dsi->next_bridge))
+			return PTR_ERR(dsi->next_bridge);
+	}
 
 	drm_bridge_add(&dsi->bridge);