Re: [PATCH v4 3/3] drm/mediatek: Implement OF graphs support for display paths

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Il 17/05/24 11:49, Michael Walle ha scritto:
Hi Angelo,

On Thu May 16, 2024 at 10:11 AM CEST, AngeloGioacchino Del Regno wrote:
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.

paths might be optional, see comment in mtk_drm_kms_init(). But with
this patch, you'll get an -EINVAL with a disabled path. See my
proposals how to fix that below.

I might not be understanding the reason behind allowing that but, per my logic, if
a board does have a path, then it's written in devicetree and enabled - otherwise,
it should not be there at all, in principle.

Can you explain a bit more extensively the reason(s) why we need to account
for disabled paths?


With these changes and the following two patches I was able to get
DisplayPort working on vdosys1. vdosys0 wasn't used at all.
https://lore.kernel.org/r/20240516145824.1669263-1-mwalle@xxxxxxxxxx/
https://lore.kernel.org/r/20240517093024.1702750-1-mwalle@xxxxxxxxxx/

I've already successfully tested a former version with DSI output on
vdosys0.

Thanks for working on this!


Thank you for helping with the testing! :-)

Cheers,
Angelo

+/**
+ * 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_err(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 might not be disabled. In that case, don't check the last
  * entry but just report the missing device. */
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);
+		of_node_put(ep_node);
+		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)
+		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)
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)
likewise

+			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)
likewise

+			return ret;
+	}
+
+	return 0;
+}

-michael






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