[PATCH v4 09/11] drm/bridge: tc358767: Detect bridge mode from connected endpoints in DT

[Marek Vasut]

The TC358767/TC358867/TC9595 are all capable of operating in multiple
modes, DPI-to-(e)DP, DSI-to-(e)DP, DSI-to-DPI. Only the first mode is
currently supported. It is possible to find out the mode in which the
bridge should be operated by testing connected endpoints in DT.

Port allocation:
port at 0 - DSI input
port at 1 - DPI input/output
port at 2 - eDP output

Possible connections:
DPI -> port at 1 -> port at 2 -> eDP :: [port at 0 is not connected]
DSI -> port at 0 -> port at 2 -> eDP :: [port at 1 is not connected]
DSI -> port at 0 -> port at 1 -> DPI :: [port at 2 is not connected]

Add function to determine the bridge mode based on connected endpoints.

Reviewed-by: Lucas Stach <l.stach at pengutronix.de>
Tested-by: Lucas Stach <l.stach at pengutronix.de> # In both DPI to eDP and DSI to DPI mode.
Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Jonas Karlman <jonas at kwiboo.se>
Cc: Laurent Pinchart <Laurent.pinchart at ideasonboard.com>
Cc: Maxime Ripard <maxime at cerno.tech>
Cc: Neil Armstrong <narmstrong at baylibre.com>
Cc: Sam Ravnborg <sam at ravnborg.org>
---
V2: - New patch
V3: - Add RB from Lucas
V4: - Add TB from Lucas
---
 drivers/gpu/drm/bridge/tc358767.c | 46 ++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index 8c468f77618d2..dd324cf16e4d0 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1621,6 +1621,50 @@ static int tc_probe_edp_bridge_endpoint(struct tc_data *tc)
 	return ret;
 }
 
+static int tc_probe_bridge_endpoint(struct tc_data *tc)
+{
+	struct device *dev = tc->dev;
+	struct of_endpoint endpoint;
+	struct device_node *node = NULL;
+	const u8 mode_dpi_to_edp = BIT(1) | BIT(2);
+	const u8 mode_dsi_to_edp = BIT(0) | BIT(2);
+	const u8 mode_dsi_to_dpi = BIT(0) | BIT(1);
+	u8 mode = 0;
+
+	/*
+	 * Determine bridge configuration.
+	 *
+	 * Port allocation:
+	 * port at 0 - DSI input
+	 * port at 1 - DPI input/output
+	 * port at 2 - eDP output
+	 *
+	 * Possible connections:
+	 * DPI -> port at 1 -> port at 2 -> eDP :: [port at 0 is not connected]
+	 * DSI -> port at 0 -> port at 2 -> eDP :: [port at 1 is not connected]
+	 * DSI -> port at 0 -> port at 1 -> DPI :: [port at 2 is not connected]
+	 */
+
+	for_each_endpoint_of_node(dev->of_node, node) {
+		of_graph_parse_endpoint(node, &endpoint);
+		if (endpoint.port > 2)
+			return -EINVAL;
+
+		mode |= BIT(endpoint.port);
+	}
+
+	if (mode == mode_dpi_to_edp)
+		return tc_probe_edp_bridge_endpoint(tc);
+	else if (mode == mode_dsi_to_dpi)
+		dev_warn(dev, "The mode DSI-to-DPI is not supported!\n");
+	else if (mode == mode_dsi_to_edp)
+		dev_warn(dev, "The mode DSI-to-(e)DP is not supported!\n");
+	else
+		dev_warn(dev, "Invalid mode (0x%x) is not supported!\n", mode);
+
+	return -EINVAL;
+}
+
 static int tc_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
@@ -1633,7 +1677,7 @@ static int tc_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 	tc->dev = dev;
 
-	ret = tc_probe_edp_bridge_endpoint(tc);
+	ret = tc_probe_bridge_endpoint(tc);
 	if (ret)
 		return ret;
 
-- 
2.35.1