gpu: drm: apple: Use components to avoid deferred probing

There was a report of a race between DRM device registration (and
removal of the simpledrm device) and GDM startup.

The component based device binding ensures that all necessary devices
are bind in the probe method of the last missing component.

Technically the piodma-mapper should be a component of dcp but since it
is only used for its iommu it can be a component of the display
subsystem.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/gpu/drm/apple/apple_drv.c

@@ -7,8 +7,9 @@
  * Copyright (C) 2014 Endless Mobile
  */
 
-#include <linux/module.h>
+#include <linux/component.h>
 #include <linux/dma-mapping.h>
+#include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 
@@ -390,46 +391,55 @@ static int apple_get_fb_resource(struct device *dev, const char *name,
 	return ret;
 }
 
+static const struct of_device_id apple_dcp_id_tbl[] = {
+	{ .compatible = "apple,dcp" },
+	{},
+};
 
-static int apple_platform_probe(struct platform_device *pdev)
+static int apple_drm_init_dcp(struct device *dev)
 {
-	struct device *dev = &pdev->dev;
-	struct apple_drm_private *apple;
-	struct resource fb_r;
-	resource_size_t fb_size;
+	struct apple_drm_private *apple = dev_get_drvdata(dev);
 	struct platform_device *dcp[MAX_COPROCESSORS];
-	int ret, nr_dcp, i;
-
-	for (nr_dcp = 0; nr_dcp < MAX_COPROCESSORS; ++nr_dcp) {
-		struct device_node *np;
-		struct device_link *dcp_link;
+	struct device_node *np;
+	int ret, num_dcp = 0;
 
-		np = of_parse_phandle(dev->of_node, "apple,coprocessors",
-				      nr_dcp);
-
-		if (!np)
-			break;
+	for_each_matching_node(np, apple_dcp_id_tbl) {
+		if (!of_device_is_available(np)) {
+			of_node_put(np);
+			continue;
+		}
 
-		dcp[nr_dcp] = of_find_device_by_node(np);
+		dcp[num_dcp] = of_find_device_by_node(np);
+		of_node_put(np);
+		if (!dcp[num_dcp])
+			continue;
 
-		if (!dcp[nr_dcp])
-			return -ENODEV;
+		ret = apple_probe_per_dcp(dev, &apple->drm, dcp[num_dcp],
+					  num_dcp);
+		if (ret)
+			continue;
 
-		dcp_link = device_link_add(dev, &dcp[nr_dcp]->dev,
-					   DL_FLAG_AUTOREMOVE_CONSUMER);
-		if (!dcp_link) {
-			dev_err(dev, "Failed to link to DCP %d device", nr_dcp);
-			return -EINVAL;
-		}
+		ret = dcp_start(dcp[num_dcp]);
+		if (ret)
+			continue;
 
-		if (dcp_link->supplier->links.status != DL_DEV_DRIVER_BOUND)
-			return -EPROBE_DEFER;
+		num_dcp++;
 	}
 
-	/* Need at least 1 DCP for a display subsystem */
-	if (nr_dcp < 1)
+	if (num_dcp < 1)
 		return -ENODEV;
 
+
+	return 0;
+}
+
+static int apple_drm_init(struct device *dev)
+{
+	struct apple_drm_private *apple;
+	struct resource fb_r;
+	resource_size_t fb_size;
+	int ret;
+
 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(36));
 	if (ret)
 		return ret;
@@ -438,21 +448,25 @@ static int apple_platform_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	fb_size = fb_r.end - fb_r.start + 1;
-	ret = drm_aperture_remove_conflicting_framebuffers(fb_r.start, fb_size,
-						false, &apple_drm_driver);
-	if (ret) {
-		dev_err(dev, "Failed remove fb: %d\n", ret);
-		return ret;
-	}
-
 	apple = devm_drm_dev_alloc(dev, &apple_drm_driver,
 				   struct apple_drm_private, drm);
 	if (IS_ERR(apple))
 		return PTR_ERR(apple);
 
 	dev_set_drvdata(dev, apple);
 
+	ret = component_bind_all(dev, apple);
+	if (ret)
+		return ret;
+
+	fb_size = fb_r.end - fb_r.start + 1;
+	ret = drm_aperture_remove_conflicting_framebuffers(fb_r.start, fb_size,
+						false, &apple_drm_driver);
+	if (ret) {
+		dev_err(dev, "Failed remove fb: %d\n", ret);
+		goto err_unbind;
+	}
+
 	ret = drmm_mode_config_init(&apple->drm);
 	if (ret)
 		goto err_unload;
@@ -477,17 +491,9 @@ static int apple_platform_probe(struct platform_device *pdev)
 	apple->drm.mode_config.funcs = &apple_mode_config_funcs;
 	apple->drm.mode_config.helper_private = &apple_mode_config_helpers;
 
-	for (i = 0; i < nr_dcp; ++i) {
-		ret = apple_probe_per_dcp(dev, &apple->drm, dcp[i], i);
-
-		if (ret)
-			goto err_unload;
-
-		ret = dcp_start(dcp[i]);
-
-		if (ret)
-			goto err_unload;
-	}
+	ret = apple_drm_init_dcp(dev);
+	if (ret)
+		goto err_unload;
 
 	drm_mode_config_reset(&apple->drm);
 
@@ -501,14 +507,96 @@ static int apple_platform_probe(struct platform_device *pdev)
 
 err_unload:
 	drm_dev_put(&apple->drm);
+err_unbind:
+	component_unbind_all(dev, NULL);
 	return ret;
 }
 
-static int apple_platform_remove(struct platform_device *pdev)
+static void apple_drm_uninit(struct device *dev)
 {
-	struct apple_drm_private *apple = platform_get_drvdata(pdev);
+	struct apple_drm_private *apple = dev_get_drvdata(dev);
 
 	drm_dev_unregister(&apple->drm);
+	drm_atomic_helper_shutdown(&apple->drm);
+
+	component_unbind_all(dev, NULL);
+
+	dev_set_drvdata(dev, NULL);
+}
+
+static int apple_drm_bind(struct device *dev)
+{
+	return apple_drm_init(dev);
+}
+
+static void apple_drm_unbind(struct device *dev)
+{
+	apple_drm_uninit(dev);
+}
+
+const struct component_master_ops apple_drm_ops = {
+	.bind	= apple_drm_bind,
+	.unbind	= apple_drm_unbind,
+};
+
+static const struct of_device_id apple_component_id_tbl[] = {
+	{ .compatible = "apple,dcp-piodma" },
+	{},
+};
+
+static int add_display_components(struct device *dev,
+				  struct component_match **matchptr)
+{
+	struct device_node *np;
+
+	for_each_matching_node(np, apple_component_id_tbl) {
+		if (of_device_is_available(np))
+			drm_of_component_match_add(dev, matchptr,
+						   component_compare_of, np);
+		of_node_put(np);
+	}
+
+	return 0;
+}
+
+static int add_dcp_components(struct device *dev,
+			      struct component_match **matchptr)
+{
+	struct device_node *np;
+	int num = 0;
+
+	for_each_matching_node(np, apple_dcp_id_tbl) {
+		if (of_device_is_available(np)) {
+			drm_of_component_match_add(dev, matchptr,
+						   component_compare_of, np);
+			num++;
+		}
+		of_node_put(np);
+	}
+
+	return num;
+}
+
+static int apple_platform_probe(struct platform_device *pdev)
+{
+	struct device *mdev = &pdev->dev;
+	struct component_match *match = NULL;
+	int num_dcp;
+
+	/* add PIODMA mapper components */
+	add_display_components(mdev, &match);
+
+	/* add DCP components, handle less than 1 as probe error */
+	num_dcp = add_dcp_components(mdev, &match);
+	if (num_dcp < 1)
+		return -ENODEV;
+
+	return component_master_add_with_match(mdev, &apple_drm_ops, match);
+}
+
+static int apple_platform_remove(struct platform_device *pdev)
+{
+	component_master_del(&pdev->dev, &apple_drm_ops);
 
 	return 0;
 }
@@ -524,14 +612,19 @@ static int apple_platform_suspend(struct device *dev)
 {
 	struct apple_drm_private *apple = dev_get_drvdata(dev);
 
-	return drm_mode_config_helper_suspend(&apple->drm);
+	if (apple)
+		return drm_mode_config_helper_suspend(&apple->drm);
+
+	return 0;
 }
 
 static int apple_platform_resume(struct device *dev)
 {
 	struct apple_drm_private *apple = dev_get_drvdata(dev);
 
-	drm_mode_config_helper_resume(&apple->drm);
+	if (apple)
+		drm_mode_config_helper_resume(&apple->drm);
+
 	return 0;
 }
 

drivers/gpu/drm/apple/dcp-internal.h

@@ -84,7 +84,6 @@ struct dcp_brightness {
 struct apple_dcp {
 	struct device *dev;
 	struct platform_device *piodma;
-	struct device_link *piodma_link;
 	struct apple_rtkit *rtk;
 	struct apple_crtc *crtc;
 	struct apple_connector *connector;