drm: rcar-du: Add probe deferral debug messages

Print a message when the HDMI I2C slave encoder can't be found to help
debugging probe deferral issues.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_hdmienc.c b/drivers/gpu/drm/rcar-du/rcar_du_hdmienc.c
index 065b3a1d6134..461662d231e2 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_hdmienc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_hdmienc.c
@@ -131,12 +131,19 @@ int rcar_du_hdmienc_init(struct rcar_du_device *rcdu,
 
         /* Locate the slave I2C device and driver. */
         i2c_slave = of_find_i2c_device_by_node(np);
-        if (!i2c_slave || !i2c_get_clientdata(i2c_slave))
+        if (!i2c_slave || !i2c_get_clientdata(i2c_slave)) {
+                dev_dbg(rcdu->dev,
+                        "can't get I2C slave for %s, deferring probe\n",
+                        of_node_full_name(np));
                 return -EPROBE_DEFER;
+        }
 
         hdmienc->dev = &i2c_slave->dev;
 
         if (hdmienc->dev->driver == NULL) {
+                dev_dbg(rcdu->dev,
+                        "I2C slave %s not probed yet, deferring probe\n",
+                        dev_name(hdmienc->dev));
                 ret = -EPROBE_DEFER;
                 goto error;
         }