[PATCH 5/8] video: stm32: ltdc: properly search the first available panel

[Raphael Gallais-Pou]

Initially there was only one DSI bridge with one panel attached to this
device. This explained the call to uclass_first_device_err(UCLASS_PANEL,
...) which worked fine at the time.

Now that multiple bridges and panels, with different technologies, can
be plugged onto the board this way to get the panel device is outdated.

The lookup is done is two steps. First we cirle through the
UCLASS_VIDEO_BRIDGE, and once we get one, we search through its
endpoints until we get a UCLASS_PANEL device available.

Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou at foss.st.com>
---
 drivers/video/stm32/stm32_ltdc.c | 136 +++++++++++++++++++++++++++++++++++----
 1 file changed, 125 insertions(+), 11 deletions(-)

diff --git a/drivers/video/stm32/stm32_ltdc.c b/drivers/video/stm32/stm32_ltdc.c
index d9ba5c4ef53558fe8b5565d47b022699d9e4ea0e..cdcfde678fb59ad884125e7c26f43710d76ba246 100644
--- a/drivers/video/stm32/stm32_ltdc.c
+++ b/drivers/video/stm32/stm32_ltdc.c
@@ -17,6 +17,7 @@
 #include <video_bridge.h>
 #include <asm/io.h>
 #include <dm/device-internal.h>
+#include <dm/uclass-internal.h>
 #include <dm/device_compat.h>
 #include <linux/bitops.h>
 #include <linux/printk.h>
@@ -495,6 +496,101 @@ static void stm32_ltdc_set_layer1(struct stm32_ltdc_priv *priv, ulong fb_addr)
 	setbits_le32(priv->regs + LTDC_L1CR, LXCR_LEN);
 }
 
+static int stm32_ltdc_get_remote_device(struct udevice *dev, ofnode ep_node,
+					enum uclass_id id, struct udevice **remote_dev)
+{
+	u32 remote_phandle;
+	ofnode remote;
+	int ret = 0;
+
+	ret = ofnode_read_u32(ep_node, "remote-endpoint", &remote_phandle);
+	if (ret) {
+		dev_err(dev, "%s(%s): Could not find remote-endpoint property\n",
+			__func__, dev_read_name(dev));
+		return ret;
+	}
+
+	remote = ofnode_get_by_phandle(remote_phandle);
+	if (!ofnode_valid(remote))
+		return -EINVAL;
+
+	while (ofnode_valid(remote)) {
+		remote = ofnode_get_parent(remote);
+		if (!ofnode_valid(remote)) {
+			dev_dbg(dev, "%s(%s): no uclass_id %d for remote-endpoint\n",
+				__func__, dev_read_name(dev), id);
+			continue;
+		}
+
+		ret = uclass_find_device_by_ofnode(id, remote, remote_dev);
+		if (*remote_dev && !ret) {
+			ret = uclass_get_device_by_ofnode(id, remote, remote_dev);
+			if (ret)
+				dev_dbg(dev, "%s(%s): failed to get remote device %s\n",
+					__func__, dev_read_name(dev), dev_read_name(*remote_dev));
+			break;
+		}
+	};
+
+	return ret;
+}
+
+static int stm32_ltdc_get_panel(struct udevice *dev, struct udevice **panel)
+{
+	ofnode ep_node, node, ports;
+	int ret = 0;
+
+	if (!dev)
+		return -EINVAL;
+
+	ports = ofnode_find_subnode(dev_ofnode(dev), "ports");
+	if (!ofnode_valid(ports)) {
+		dev_err(dev, "Remote bridge subnode\n");
+		return ret;
+	}
+
+	for (node = ofnode_first_subnode(ports);
+	     ofnode_valid(node);
+	     node = dev_read_next_subnode(node)) {
+		ep_node = ofnode_first_subnode(node);
+		if (!ofnode_valid(ep_node))
+			continue;
+
+		ret = stm32_ltdc_get_remote_device(dev, ep_node, UCLASS_PANEL, panel);
+	}
+
+	/* Sanity check, we can get out of the loop without having a clean ofnode */
+	if (!(*panel))
+		ret = -EINVAL;
+	else
+		if (!ofnode_valid(dev_ofnode(*panel)))
+			ret = -EINVAL;
+
+	return ret;
+}
+
+static int stm32_ltdc_display_init(struct udevice *dev, ofnode *ep_node,
+				   struct udevice **panel, struct udevice **bridge)
+{
+	int ret;
+
+	if (*panel)
+		return -EINVAL;
+
+	if (IS_ENABLED(CONFIG_VIDEO_BRIDGE)) {
+		ret = stm32_ltdc_get_remote_device(dev, *ep_node, UCLASS_VIDEO_BRIDGE, bridge);
+		if (ret)
+			return ret;
+
+		ret = stm32_ltdc_get_panel(*bridge, panel);
+	} else {
+		/* no bridge, search a panel from display controller node */
+		ret = stm32_ltdc_get_remote_device(dev, *ep_node, UCLASS_PANEL, panel);
+	}
+
+	return ret;
+}
+
 #if IS_ENABLED(CONFIG_TARGET_STM32F469_DISCOVERY)
 static int stm32_ltdc_alloc_fb(struct udevice *dev)
 {
@@ -532,6 +628,7 @@ static int stm32_ltdc_probe(struct udevice *dev)
 	struct display_timing timings;
 	struct clk pclk, bclk;
 	struct reset_ctl rst;
+	ofnode node, port;
 	ulong rate;
 	int ret;
 
@@ -568,7 +665,7 @@ static int stm32_ltdc_probe(struct udevice *dev)
 	}
 
 	priv->hw_version = readl(priv->regs + LTDC_IDR);
-	debug("%s: LTDC hardware 0x%x\n", __func__, priv->hw_version);
+	dev_dbg(dev, "%s: LTDC hardware 0x%x\n", __func__, priv->hw_version);
 
 	switch (priv->hw_version) {
 	case HWVER_10200:
@@ -589,13 +686,35 @@ static int stm32_ltdc_probe(struct udevice *dev)
 		return -ENODEV;
 	}
 
-	ret = uclass_first_device_err(UCLASS_PANEL, &panel);
-	if (ret) {
-		if (ret != -ENODEV)
-			dev_err(dev, "panel device error %d\n", ret);
-		return ret;
+	/*
+	 * Try all the ports until one working.
+	 *
+	 * This is done in two times. First is checks for the
+	 * UCLASS_VIDEO_BRIDGE available, and then for this bridge
+	 * it scans for a UCLASS_PANEL.
+	 */
+
+	port = dev_read_subnode(dev, "port");
+	if (!ofnode_valid(port)) {
+		dev_err(dev, "%s(%s): 'port' subnode not found\n",
+			__func__, dev_read_name(dev));
+		return -EINVAL;
 	}
 
+	for (node = ofnode_first_subnode(port);
+	     ofnode_valid(node);
+	     node = dev_read_next_subnode(node)) {
+		ret = stm32_ltdc_display_init(dev, &node, &panel, &bridge);
+		if (ret)
+			dev_dbg(dev, "Device failed ret=%d\n", ret);
+		else
+			break;
+	}
+
+	/* Sanity check */
+	if (ret)
+		return ret;
+
 	ret = panel_get_display_timing(panel, &timings);
 	if (ret) {
 		ret = ofnode_decode_display_timing(dev_ofnode(panel),
@@ -624,11 +743,6 @@ static int stm32_ltdc_probe(struct udevice *dev)
 	reset_deassert(&rst);
 
 	if (IS_ENABLED(CONFIG_VIDEO_BRIDGE)) {
-		ret = uclass_get_device(UCLASS_VIDEO_BRIDGE, 0, &bridge);
-		if (ret)
-			dev_dbg(dev,
-				"No video bridge, or no backlight on bridge\n");
-
 		if (bridge) {
 			ret = video_bridge_attach(bridge);
 			if (ret) {

-- 
2.25.1