[PATCH v5 2/6] drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>
Cc: dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v5 2/6] drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence
Date: Sat, 18 Apr 2020 20:06:59 +0300	[thread overview]
Message-ID: <20200418170703.1583-3-digetx@gmail.com> (raw)
In-Reply-To: <20200418170703.1583-1-digetx@gmail.com>

When graph isn't defined in a device-tree, the of_graph_get_remote_node()
prints a noisy error message, telling that port node is not found. This is
undesirable behaviour in our case because absence of a panel/bridge graph
is a valid case. Let's check presence of the local port in a device-tree
before proceeding with parsing the graph.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/gpu/drm/drm_of.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index b50b44e76279..e0652c38f357 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -239,13 +239,24 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 				struct drm_bridge **bridge)
 {
 	int ret = -EPROBE_DEFER;
-	struct device_node *remote;
+	struct device_node *local, *remote;
 
 	if (!panel && !bridge)
 		return -EINVAL;
 	if (panel)
 		*panel = NULL;
 
+	/*
+	 * of_graph_get_remote_node() produces a noisy error message if port
+	 * node isn't found and the absence of the port is a legit case here,
+	 * so at first we silently check presence of the local port.
+	 */
+	local = of_graph_get_local_port(np);
+	if (!local)
+		return -ENODEV;
+
+	of_node_put(local);
+
 	remote = of_graph_get_remote_node(np, port, endpoint);
 	if (!remote)
 		return -ENODEV;
-- 
2.26.0
