drm/vc4: Set up the DSI host at pdev probe time, not component bind.

We need the following things to happen in sequence:

DSI host creation
DSI device creation in the panel driver (needs DSI host)
DSI device attach from panel to host.
DSI drm_panel_add()
DSI encoder creation
DSI encoder's DRM panel/bridge attach

Unless we allow device creation while the host isn't up yet, we need
to break the -EPROBE_DEFER deadlock between the panel driver looking
up the host and the host driver looking up the panel.  We can do so by
moving the DSI host creation outside of the component bind loop, and
the panel/bridge lookup/attach into the component bind process.
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20170815234722.20700-3-eric@anholt.netReviewed-by: Archit Taneja <architt@codeaurora.org>

drivers/gpu/drm/vc4/vc4_dsi.c

@@ -33,6 +33,7 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_mipi_dsi.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
@@ -504,7 +505,6 @@ struct vc4_dsi {
 	struct mipi_dsi_host dsi_host;
 	struct drm_encoder *encoder;
 	struct drm_bridge *bridge;
-	bool is_panel_bridge;
 
 	void __iomem *regs;
 
@@ -1289,7 +1289,6 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
 			       struct mipi_dsi_device *device)
 {
 	struct vc4_dsi *dsi = host_to_dsi(host);
-	int ret = 0;
 
 	dsi->lanes = device->lanes;
 	dsi->channel = device->channel;
@@ -1324,34 +1323,12 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
 		return 0;
 	}
 
-	dsi->bridge = of_drm_find_bridge(device->dev.of_node);
-	if (!dsi->bridge) {
-		struct drm_panel *panel =
-			of_drm_find_panel(device->dev.of_node);
-
-		dsi->bridge = drm_panel_bridge_add(panel,
-						   DRM_MODE_CONNECTOR_DSI);
-		if (IS_ERR(dsi->bridge)) {
-			ret = PTR_ERR(dsi->bridge);
-			dsi->bridge = NULL;
-			return ret;
-		}
-		dsi->is_panel_bridge = true;
-	}
-
-	return drm_bridge_attach(dsi->encoder, dsi->bridge, NULL);
+	return 0;
 }
 
 static int vc4_dsi_host_detach(struct mipi_dsi_host *host,
 			       struct mipi_dsi_device *device)
 {
-	struct vc4_dsi *dsi = host_to_dsi(host);
-
-	if (dsi->is_panel_bridge) {
-		drm_panel_bridge_remove(dsi->bridge);
-		dsi->bridge = NULL;
-	}
-
 	return 0;
 }
 
@@ -1493,16 +1470,13 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct drm_device *drm = dev_get_drvdata(master);
 	struct vc4_dev *vc4 = to_vc4_dev(drm);
-	struct vc4_dsi *dsi;
+	struct vc4_dsi *dsi = dev_get_drvdata(dev);
 	struct vc4_dsi_encoder *vc4_dsi_encoder;
+	struct drm_panel *panel;
 	const struct of_device_id *match;
 	dma_cap_mask_t dma_mask;
 	int ret;
 
-	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
-	if (!dsi)
-		return -ENOMEM;
-
 	match = of_match_device(vc4_dsi_dt_match, dev);
 	if (!match)
 		return -ENODEV;
@@ -1517,7 +1491,6 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 	vc4_dsi_encoder->dsi = dsi;
 	dsi->encoder = &vc4_dsi_encoder->base.base;
 
-	dsi->pdev = pdev;
 	dsi->regs = vc4_ioremap_regs(pdev, 0);
 	if (IS_ERR(dsi->regs))
 		return PTR_ERR(dsi->regs);
@@ -1598,6 +1571,18 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 		return ret;
 	}
 
+	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
+					  &panel, &dsi->bridge);
+	if (ret)
+		return ret;
+
+	if (panel) {
+		dsi->bridge = devm_drm_panel_bridge_add(dev, panel,
+							DRM_MODE_CONNECTOR_DSI);
+		if (IS_ERR(dsi->bridge))
+			return PTR_ERR(dsi->bridge);
+	}
+
 	/* The esc clock rate is supposed to always be 100Mhz. */
 	ret = clk_set_rate(dsi->escape_clock, 100 * 1000000);
 	if (ret) {
@@ -1616,12 +1601,11 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 			 DRM_MODE_ENCODER_DSI, NULL);
 	drm_encoder_helper_add(dsi->encoder, &vc4_dsi_encoder_helper_funcs);
 
-	dsi->dsi_host.ops = &vc4_dsi_host_ops;
-	dsi->dsi_host.dev = dev;
-
-	mipi_dsi_host_register(&dsi->dsi_host);
-
-	dev_set_drvdata(dev, dsi);
+	ret = drm_bridge_attach(dsi->encoder, dsi->bridge, NULL);
+	if (ret) {
+		dev_err(dev, "bridge attach failed: %d\n", ret);
+		return ret;
+	}
 
 	pm_runtime_enable(dev);
 
@@ -1639,8 +1623,6 @@ static void vc4_dsi_unbind(struct device *dev, struct device *master,
 
 	vc4_dsi_encoder_destroy(dsi->encoder);
 
-	mipi_dsi_host_unregister(&dsi->dsi_host);
-
 	if (dsi->port == 1)
 		vc4->dsi1 = NULL;
 }
@@ -1652,12 +1634,47 @@ static const struct component_ops vc4_dsi_ops = {
 
 static int vc4_dsi_dev_probe(struct platform_device *pdev)
 {
-	return component_add(&pdev->dev, &vc4_dsi_ops);
+	struct device *dev = &pdev->dev;
+	struct vc4_dsi *dsi;
+	int ret;
+
+	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
+	if (!dsi)
+		return -ENOMEM;
+	dev_set_drvdata(dev, dsi);
+
+	dsi->pdev = pdev;
+
+	/* Note, the initialization sequence for DSI and panels is
+	 * tricky.  The component bind above won't get past its
+	 * -EPROBE_DEFER until the panel/bridge probes.  The
+	 * panel/bridge will return -EPROBE_DEFER until it has a
+	 * mipi_dsi_host to register its device to.  So, we register
+	 * the host during pdev probe time, so vc4 as a whole can then
+	 * -EPROBE_DEFER its component bind process until the panel
+	 * successfully attaches.
+	 */
+	dsi->dsi_host.ops = &vc4_dsi_host_ops;
+	dsi->dsi_host.dev = dev;
+	mipi_dsi_host_register(&dsi->dsi_host);
+
+	ret = component_add(&pdev->dev, &vc4_dsi_ops);
+	if (ret) {
+		mipi_dsi_host_unregister(&dsi->dsi_host);
+		return ret;
+	}
+
+	return 0;
 }
 
 static int vc4_dsi_dev_remove(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
+	struct vc4_dsi *dsi = dev_get_drvdata(dev);
+
 	component_del(&pdev->dev, &vc4_dsi_ops);
+	mipi_dsi_host_unregister(&dsi->dsi_host);
+
 	return 0;
 }