[PATCH v6 3/5] drm/bridge: analogix_dp: Restore mandatory samsung DP DT properties

[Damon Ding]

Revert the change that made samsung,link-rate and samsung,lane-count
optional for Exynos DP. Add error checking to fail probe early if the
required DT properties are missing.

If these properties are zero, &link_train.link_rate and
&link_train.lane_count used in the subsequent link training flow will
also be zero, resulting in link training failure. Although all existing
Exynos DP DT nodes already contain these two properties, this potential
logic issue still needs to be fixed.

Fixes: 0d0abd894ead ("drm: bridge: analogix/dp: add max link rate and lane count limit for RK3288")
Signed-off-by: Damon Ding <damon.ding at rock-chips.com>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 8d3d4a6e6ca2..5240efcd3861 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1244,6 +1244,7 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
 {
 	struct device_node *dp_node = dp->dev->of_node;
 	struct video_info *video_info = &dp->video_info;
+	u32 val;
 
 	switch (dp->plat_data->dev_type) {
 	case RK3288_DP:
@@ -1265,10 +1266,14 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
 		 * NOTE: those property parseing code is used for
 		 * providing backward compatibility for samsung platform.
 		 */
-		of_property_read_u32(dp_node, "samsung,link-rate",
-				     &video_info->max_link_rate);
-		of_property_read_u32(dp_node, "samsung,lane-count",
-				     &video_info->max_lane_count);
+		if (of_property_read_u32(dp_node, "samsung,link-rate", &val))
+			return dev_err_probe(dp->dev, -EINVAL,
+					     "Failed to get samsung,link-rate\n");
+		video_info->max_link_rate = val;
+		if (of_property_read_u32(dp_node, "samsung,lane-count", &val))
+			return dev_err_probe(dp->dev, -EINVAL,
+					     "Failed to get samsung,lane-count\n");
+		video_info->max_lane_count = val;
 		break;
 	}
 
-- 
2.34.1