[PATCH v3 08/15] drm/rockchip: analogix_dp: Add support to get panel from the DP AUX bus

[Damon Ding]

The rockchip_dp_of_panel_on_aux_bus() helps to check whether the DT
configurations related to the DP AUX bus are correct or not.

If failed to get the panel from the platform bus, it is good to try
the DP AUX bus. Then, the probing process will continue until it enters
the analogix_dp_bind(), where devm_of_dp_aux_populate_bus() is called
after &analogix_dp_device.aux has been initialized.

Signed-off-by: Damon Ding <damon.ding at rock-chips.com>
---
 .../gpu/drm/rockchip/analogix_dp-rockchip.c   | 24 +++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
index ba5263f85ee2..60c902abf40b 100644
--- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
@@ -317,6 +317,24 @@ static const struct drm_encoder_helper_funcs rockchip_dp_encoder_helper_funcs =
 	.atomic_check = rockchip_dp_drm_encoder_atomic_check,
 };
 
+static bool rockchip_dp_of_panel_on_aux_bus(const struct device_node *np)
+{
+	struct device_node *bus_node, *panel_node;
+
+	bus_node = of_get_child_by_name(np, "aux-bus");
+	if (!bus_node)
+		return false;
+
+	panel_node = of_get_child_by_name(bus_node, "panel");
+	of_node_put(bus_node);
+	if (!panel_node)
+		return false;
+
+	of_node_put(panel_node);
+
+	return true;
+}
+
 static int rockchip_dp_of_probe(struct rockchip_dp_device *dp)
 {
 	struct device *dev = dp->dev;
@@ -435,8 +453,10 @@ static int rockchip_dp_probe(struct platform_device *pdev)
 		return -ENODEV;
 
 	ret = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &panel, NULL);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		if (!rockchip_dp_of_panel_on_aux_bus(dev->of_node))
+			return ret;
+	}
 
 	dp = devm_kzalloc(dev, sizeof(*dp), GFP_KERNEL);
 	if (!dp)
-- 
2.34.1