[PATCH] Revert "drm/imx: Remove of_node assignment from ipuv3-crtc driver probe"

[Fabio Estevam <fabio.estevam@nxp.com>]

Commit 407c9eba789767 ("drm/imx: Remove of_node assignment from ipuv3-crtc
driver probe") causes the IPU to be non-functional, so better to 
revert it to avoid such regression.

This reverts commit 407c9eba789767feb68b42eb2d65db68584e06c0.

Cc: <stable@vger.kernel.org> # 4.4.x
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
---
 drivers/gpu/drm/imx/ipuv3-crtc.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/imx/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3-crtc.c
index dee8e8b..006753d 100644
--- a/drivers/gpu/drm/imx/ipuv3-crtc.c
+++ b/drivers/gpu/drm/imx/ipuv3-crtc.c
@@ -520,6 +520,28 @@ err_put_resources:
 	return ret;
 }
 
+static struct device_node *ipu_drm_get_port_by_id(struct device_node *parent,
+						  int port_id)
+{
+	struct device_node *port;
+	int id, ret;
+
+	port = of_get_child_by_name(parent, "port");
+	while (port) {
+		ret = of_property_read_u32(port, "reg", &id);
+		if (!ret && id == port_id)
+			return port;
+
+		do {
+			port = of_get_next_child(parent, port);
+			if (!port)
+				return NULL;
+		} while (of_node_cmp(port->name, "port"));
+	}
+
+	return NULL;
+}
+
 static int ipu_drm_bind(struct device *dev, struct device *master, void *data)
 {
 	struct ipu_client_platformdata *pdata = dev->platform_data;
@@ -562,11 +584,23 @@ static const struct component_ops ipu_crtc_ops = {
 static int ipu_drm_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct ipu_client_platformdata *pdata = dev->platform_data;
 	int ret;
 
 	if (!dev->platform_data)
 		return -EINVAL;
 
+	if (!dev->of_node) {
+		/* Associate crtc device with the corresponding DI port node */
+		dev->of_node = ipu_drm_get_port_by_id(dev->parent->of_node,
+						      pdata->di + 2);
+		if (!dev->of_node) {
+			dev_err(dev, "missing port@%d node in %s\n",
+				pdata->di + 2, dev->parent->of_node->full_name);
+			return -ENODEV;
+		}
+	}
+
 	ret = dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
 	if (ret)
 		return ret;
-- 
1.9.1