[PATCH v1 2/4] drm/bridge: dw-hdmi: Allow &dw_hdmi_plat_data.output_port = 0 without DRM_BRIDGE_ATTACH_NO_CONNECTOR

[Damon Ding]

In the previous commit, Luca split the dw-hdmi attach process into two
cases:

 A. hdmi->plat_data->output_port = 0:
    the HDMI output (port at 1) in device tree is not used

 B. hdmi->plat_data->output_port = 1:
    the HDMI output (port at 1) is parsed to find the next bridge

For Rockchip, many older platforms (RK3288, RK3399, etc.) only support
case A by default. They can support DRM_BRIDGE_ATTACH_NO_CONNECTOR flag
after adapting to the bridge connector helper. Relax this constraint in
preparation for Rockchip dw-hdmi bridge-connector adaptation.

Link: https://lore.kernel.org/all/20260402-drm-lcdif-dbanc-v3-6-27cd247a0847@bootlin.com/
Signed-off-by: Damon Ding <damon.ding at rock-chips.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index dd50dda3a4f5..20b2f9e145b0 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2912,9 +2912,8 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge,
 {
 	struct dw_hdmi *hdmi = bridge->driver_private;
 
-	/* DRM_BRIDGE_ATTACH_NO_CONNECTOR requires a remote-endpoint to the next bridge */
-	if (WARN_ON((flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) && !hdmi->plat_data->output_port))
-		return -EINVAL;
+	if ((flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) && !hdmi->plat_data->output_port)
+		return 0;
 
 	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
 		struct device_node *remote __free(device_node) =
-- 
2.34.1