drm/bridge: tc358775: Get bridge data lanes instead of the DSI host lanes

The current code assumes the data-lanes property is configured on the
DSI host side instead of the bridge side, and assumes DSI host endpoint 1.

Let's standardize on what the other bridge drivers are doing and parse the
data-lanes property for the bridge. Only if data-lanes property is not found,
let's be nice and also check the DSI host for old dtb in use and warn.

And as Dmitry pointed out, the lanes for the host and the bridge may be
different because the lanes may be swapped on the host side.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240225062008.33191-7-tony@atomide.com

1 files changed, 11 insertions, 14 deletions

diff --git a/drivers/gpu/drm/bridge/tc358775.c b/drivers/gpu/drm/bridge/tc358775.c
index 35e78b58a39c..0b7a9305bca5 100644
--- a/drivers/gpu/drm/bridge/tc358775.c
+++ b/drivers/gpu/drm/bridge/tc358775.c
@@ -525,27 +525,24 @@ tc_mode_valid(struct drm_bridge *bridge,
 static int tc358775_parse_dt(struct device_node *np, struct tc_data *tc)
 {
 	struct device_node *endpoint;
-	struct device_node *parent;
 	struct device_node *remote;
 	int dsi_lanes = -1;
 
-	/*
-	 * To get the data-lanes of dsi, we need to access the dsi0_out of port1
-	 *  of dsi0 endpoint from bridge port0 of d2l_in
-	 */
 	endpoint = of_graph_get_endpoint_by_regs(tc->dev->of_node,
 						 TC358775_DSI_IN, -1);
-	if (endpoint) {
-		/* dsi0_out node */
-		parent = of_graph_get_remote_port_parent(endpoint);
-		of_node_put(endpoint);
-		if (parent) {
-			/* dsi0 port 1 */
-			dsi_lanes = drm_of_get_data_lanes_count_ep(parent, 1, -1, 1, 4);
-			of_node_put(parent);
-		}
+	dsi_lanes = drm_of_get_data_lanes_count(endpoint, 1, 4);
+
+	/* Quirk old dtb: Use data lanes from the DSI host side instead of bridge */
+	if (dsi_lanes == -EINVAL || dsi_lanes == -ENODEV) {
+		remote = of_graph_get_remote_endpoint(endpoint);
+		dsi_lanes = drm_of_get_data_lanes_count(remote, 1, 4);
+		of_node_put(remote);
+		if (dsi_lanes >= 1)
+			dev_warn(tc->dev, "no dsi-lanes for the bridge, using host lanes\n");
 	}
 
+	of_node_put(endpoint);
+
 	if (dsi_lanes < 0)
 		return dsi_lanes;