From 11d6c660a536b3ed958c93e929d3b5b5aa967792 Mon Sep 17 00:00:00 2001
From: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Date: Thu, 16 Apr 2020 23:06:54 +0200
Subject: drm/bridge: panel: Return always an error pointer in
Git-commit: 30be3031087139061de4421bf52015931eaab569
Patch-mainline: v5.8-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
 drm_panel_bridge_add()

Since commit 89958b7cd955 ("drm/bridge: panel: Infer connector type from
panel by default"), drm_panel_bridge_add() and their variants can return
NULL and an error pointer. This is fine but none of the actual users of
the API are checking for the NULL value. Instead of change all the
users, seems reasonable to return an error pointer instead. So change
the returned value for those functions when the connector type is unknown.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200416210654.2468805-1-enric.balletbo@collabora.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/bridge/panel.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index e933f1c47f5d..1e63ed6b18aa 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -166,7 +166,7 @@ static const struct drm_bridge_funcs panel_bridge_bridge_funcs = {
  *
  * The connector type is set to @panel->connector_type, which must be set to a
  * known type. Calling this function with a panel whose connector type is
- * DRM_MODE_CONNECTOR_Unknown will return NULL.
+ * DRM_MODE_CONNECTOR_Unknown will return ERR_PTR(-EINVAL).
  *
  * See devm_drm_panel_bridge_add() for an automatically managed version of this
  * function.
@@ -174,7 +174,7 @@ static const struct drm_bridge_funcs panel_bridge_bridge_funcs = {
 struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel)
 {
 	if (WARN_ON(panel->connector_type == DRM_MODE_CONNECTOR_Unknown))
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	return drm_panel_bridge_add_typed(panel, panel->connector_type);
 }
@@ -265,7 +265,7 @@ struct drm_bridge *devm_drm_panel_bridge_add(struct device *dev,
 					     struct drm_panel *panel)
 {
 	if (WARN_ON(panel->connector_type == DRM_MODE_CONNECTOR_Unknown))
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	return devm_drm_panel_bridge_add_typed(dev, panel,
 					       panel->connector_type);
-- 
2.28.0