drm/omap: dss: Extend omapdss_of_find_source_for_first_ep() to sinks

The omapdss_of_find_source_for_first_ep() function locates the source
corresponding to the first endpoint of the first port of a device node.
We can easily extend it to locate sinks as well by passing the port
number as a parameter. This will be useful to find sinks in encoders
drivers.

Extend the function and rename it to omapdss_of_find_connected_device()
to reflect its new extended purpose.

Additionally, it is useful to differentiate between failures to return
the connected device because no link exists in the device tree for the
requested port, or because the connected device as described in the
device tree is invalid or not probed yet. Return NULL in the first case
and an error code in the second case, and update the callers
accordingly.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c b/drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c
index febb20961dc5..501c47f95130 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c
@@ -763,10 +763,10 @@ static int dsicm_connect(struct omap_dss_device *dssdev)
 	struct omap_dss_device *src;
 	int r;
 
-	src = omapdss_of_find_source_for_first_ep(dssdev->dev->of_node);
-	if (IS_ERR(src)) {
+	src = omapdss_of_find_connected_device(dssdev->dev->of_node, 0);
+	if (IS_ERR_OR_NULL(src)) {
 		dev_err(dssdev->dev, "failed to find video source\n");
-		return PTR_ERR(src);
+		return src ? PTR_ERR(src) : -EINVAL;
 	}
 
 	r = omapdss_device_connect(dssdev->dss, src, dssdev);