From 95173a7d80d32cf0f505fb9b8e13427dc8a04654 Mon Sep 17 00:00:00 2001
From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Sat, 12 Feb 2022 01:40:04 +0300
Subject: drm/msm/dp: support finding next bridge even for DP interfaces
Git-commit: d8c2f09412ebc12a71594be66fa7248b04110afa
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

It is possible to supply display-connector (bridge) to the DP interface,
add support for parsing it too.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20220211224006.1797846-4-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/msm/dp/dp_parser.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
index 901d7967370f..1056b8d5755b 100644
--- a/drivers/gpu/drm/msm/dp/dp_parser.c
+++ b/drivers/gpu/drm/msm/dp/dp_parser.c
@@ -301,17 +301,22 @@ static int dp_parser_parse(struct dp_parser *parser, int connector_type)
 		return rc;
 
 	/*
-	 * Currently we support external bridges only for eDP connectors.
+	 * External bridges are mandatory for eDP interfaces: one has to
+	 * provide at least an eDP panel (which gets wrapped into panel-bridge).
 	 *
-	 * No external bridges are expected for the DisplayPort connector,
-	 * it is physically present in a form of a DP or USB-C connector.
+	 * For DisplayPort interfaces external bridges are optional, so
+	 * silently ignore an error if one is not present (-ENODEV).
 	 */
-	if (connector_type == DRM_MODE_CONNECTOR_eDP) {
-		rc = dp_parser_find_next_bridge(parser);
-		if (rc) {
-			DRM_ERROR("DP: failed to find next bridge\n");
+	rc = dp_parser_find_next_bridge(parser);
+	if (rc == -ENODEV) {
+		if (connector_type == DRM_MODE_CONNECTOR_eDP) {
+			DRM_ERROR("eDP: next bridge is not present\n");
 			return rc;
 		}
+	} else if (rc) {
+		if (rc != -EPROBE_DEFER)
+			DRM_ERROR("DP: error parsing next bridge: %d\n", rc);
+		return rc;
 	}
 
 	/* Map the corresponding regulator information according to
-- 
2.38.1