[PATCH v1 0/4] Apply bridge-connector for the Rockchip DW-HDMI driver

[PATCH v1 0/4] Apply bridge-connector for the Rockchip DW-HDMI driver

[Damon Ding]

This patch series depends on and must be applied after:
https://lore.kernel.org/all/20260402-drm-lcdif-dbanc-v3-7-27cd247a0847@bootlin.com/
(Series [v3,00/11] drm/mxsfb/lcdif: use DRM_BRIDGE_ATTACH_NO_CONNECTOR and the bridge-connector)

Patch 1: Make DRM_BRIDGE_ATTACH_NO_CONNECTOR optional for platforms that call
         dw_hdmi_bind() to attach the dw-hdmi bridge.
Patch 2: Allow &dw_hdmi_plat_data.output_port = 0 without the attach flag
         DRM_BRIDGE_ATTACH_NO_CONNECTOR for dw-hdmi bridge.
Patch 3: Apply bridge-connector for Rockchip dw-hdmi driver, so that connector
         management is unified under bridge-connector. Treat dw-hdmi purely as
         a bridge without using its own connector helper functions, which
         partially overlaps with the bridge helper.
Patch 4: Add next bridge support for Rockchip dw-hdmi driver, so that it can
         support both the HDMI connector and additional bridge chips.

Damon Ding (4):
  drm/bridge: dw-hdmi: Pass bridge attach flags for dw_hdmi_bind()
  drm/bridge: dw-hdmi: Allow &dw_hdmi_plat_data.output_port = 0 without
    DRM_BRIDGE_ATTACH_NO_CONNECTOR
  drm/rockchip: dw_hdmi: Apply DRM_BRIDGE_ATTACH_NO_CONNECTOR and the
    bridge-connector
  drm/rockchip: dw_hdmi: Support to find the next bridge

 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c   | 10 +++----
 drivers/gpu/drm/rockchip/Kconfig            |  1 +
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 33 ++++++++++++++++++---
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c       |  2 +-
 include/drm/bridge/dw_hdmi.h                |  4 ++-
 5 files changed, 39 insertions(+), 11 deletions(-)

-- 
2.34.1

[PATCH v1 1/4] drm/bridge: dw-hdmi: Pass bridge attach flags for dw_hdmi_bind()

[Damon Ding]

For Rockchip and Allwinner platforms, the HDMI encoder attaches the
dw-hdmi bridge via dw_hdmi_bind(). This additional bridge attach flag
serves as preparation for the Rockchip dw-hdmi driver to support the
bridge-connector framework.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c   | 5 +++--
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 2 +-
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c       | 2 +-
 include/drm/bridge/dw_hdmi.h                | 4 +++-
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index ada45e8b3e2c..dd50dda3a4f5 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -3619,7 +3619,8 @@ EXPORT_SYMBOL_GPL(dw_hdmi_remove);
  */
 struct dw_hdmi *dw_hdmi_bind(struct platform_device *pdev,
 			     struct drm_encoder *encoder,
-			     const struct dw_hdmi_plat_data *plat_data)
+			     const struct dw_hdmi_plat_data *plat_data,
+			     enum drm_bridge_attach_flags flags)
 {
 	struct dw_hdmi *hdmi;
 	int ret;
@@ -3628,7 +3629,7 @@ struct dw_hdmi *dw_hdmi_bind(struct platform_device *pdev,
 	if (IS_ERR(hdmi))
 		return hdmi;
 
-	ret = drm_bridge_attach(encoder, &hdmi->bridge, NULL, 0);
+	ret = drm_bridge_attach(encoder, &hdmi->bridge, NULL, flags);
 	if (ret) {
 		dw_hdmi_remove(hdmi);
 		return ERR_PTR(ret);
diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index 0dc1eb5d2ae3..21b141b7cb9c 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -608,7 +608,7 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 
 	platform_set_drvdata(pdev, hdmi);
 
-	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data);
+	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data, 0);
 
 	/*
 	 * If dw_hdmi_bind() fails we'll never call dw_hdmi_unbind(),
diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
index 96532709c2a7..04173335f7e7 100644
--- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
+++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
@@ -188,7 +188,7 @@ static int sun8i_dw_hdmi_bind(struct device *dev, struct device *master,
 
 	platform_set_drvdata(pdev, hdmi);
 
-	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data);
+	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data, 0);
 
 	/*
 	 * If dw_hdmi_bind() fails we'll never call dw_hdmi_unbind(),
diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
index 8500dd4f99d8..e789fb451ef2 100644
--- a/include/drm/bridge/dw_hdmi.h
+++ b/include/drm/bridge/dw_hdmi.h
@@ -6,6 +6,7 @@
 #ifndef __DW_HDMI__
 #define __DW_HDMI__
 
+#include <drm/drm_bridge.h>
 #include <sound/hdmi-codec.h>
 
 struct drm_display_info;
@@ -182,7 +183,8 @@ void dw_hdmi_remove(struct dw_hdmi *hdmi);
 void dw_hdmi_unbind(struct dw_hdmi *hdmi);
 struct dw_hdmi *dw_hdmi_bind(struct platform_device *pdev,
 			     struct drm_encoder *encoder,
-			     const struct dw_hdmi_plat_data *plat_data);
+			     const struct dw_hdmi_plat_data *plat_data,
+			     enum drm_bridge_attach_flags flags);
 
 void dw_hdmi_resume(struct dw_hdmi *hdmi);
 
-- 
2.34.1

[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@1) in device tree is not used

 B. hdmi->plat_data->output_port = 1:
    the HDMI output (port@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@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

[PATCH v1 3/4] drm/rockchip: dw_hdmi: Apply DRM_BRIDGE_ATTACH_NO_CONNECTOR and the bridge-connector

[Damon Ding]

Convert this driver to DRM_BRIDGE_ATTACH_NO_CONNECTOR and to the
drm_bridge_connector framework which is the current DRM bridge best
practice.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
---
 drivers/gpu/drm/rockchip/Kconfig            |  1 +
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/Kconfig b/drivers/gpu/drm/rockchip/Kconfig
index e7f49fe845ea..69b832d0c8c4 100644
--- a/drivers/gpu/drm/rockchip/Kconfig
+++ b/drivers/gpu/drm/rockchip/Kconfig
@@ -76,6 +76,7 @@ config ROCKCHIP_DW_DP
 
 config ROCKCHIP_DW_HDMI
 	bool "Rockchip specific extensions for Synopsys DW HDMI"
+	select DRM_BRIDGE_CONNECTOR
 	help
 	  This selects support for Rockchip SoC specific extensions
 	  for the Synopsys DesignWare HDMI driver. If you want to
diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index 21b141b7cb9c..b5cfcb936078 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -13,6 +13,7 @@
 #include <linux/regulator/consumer.h>
 
 #include <drm/bridge/dw_hdmi.h>
+#include <drm/drm_bridge_connector.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_of.h>
 #include <drm/drm_probe_helper.h>
@@ -542,6 +543,7 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 	struct drm_device *drm = data;
 	struct drm_encoder *encoder;
 	struct rockchip_hdmi *hdmi;
+	struct drm_connector *connector;
 	int ret;
 
 	if (!pdev->dev.of_node)
@@ -608,7 +610,7 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 
 	platform_set_drvdata(pdev, hdmi);
 
-	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data, 0);
+	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 
 	/*
 	 * If dw_hdmi_bind() fails we'll never call dw_hdmi_unbind(),
@@ -616,12 +618,21 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 	 */
 	if (IS_ERR(hdmi->hdmi)) {
 		ret = PTR_ERR(hdmi->hdmi);
-		goto err_bind;
+		goto err_cleanup_encoder;
 	}
 
-	return 0;
+	connector = drm_bridge_connector_init(drm, encoder);
+	if (IS_ERR(connector)) {
+		ret = PTR_ERR(connector);
+		dev_err(hdmi->dev, "Failed to initialize bridge_connector\n");
+		goto err_unbind_bridge;
+	}
 
-err_bind:
+	return drm_connector_attach_encoder(connector, encoder);
+
+err_unbind_bridge:
+	dw_hdmi_unbind(hdmi->hdmi);
+err_cleanup_encoder:
 	drm_encoder_cleanup(encoder);
 
 	return ret;
-- 
2.34.1

[PATCH v1 4/4] drm/rockchip: dw_hdmi: Support to find the next bridge

[Damon Ding]

If there is a remote node connected to the HDMI output (port@1), the
&dw_hdmi_plat_data.output_port should be set to 1. This patch allows
Rockchip dw-hdmi to support the hdmi-connector and the next bridge.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
---
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index b5cfcb936078..014ac09fd733 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -544,6 +544,8 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 	struct drm_encoder *encoder;
 	struct rockchip_hdmi *hdmi;
 	struct drm_connector *connector;
+	struct device_node *remote;
+	struct drm_bridge *next_bridge;
 	int ret;
 
 	if (!pdev->dev.of_node)
@@ -610,6 +612,18 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 
 	platform_set_drvdata(pdev, hdmi);
 
+	remote = of_graph_get_remote_node(hdmi->dev->of_node, 1, -1);
+	if (remote) {
+		of_node_put(remote);
+
+		ret = drm_of_find_panel_or_bridge(hdmi->dev->of_node, 1, 0,
+						  NULL, &next_bridge);
+		if (ret && ret != -ENODEV)
+			goto err_cleanup_encoder;
+
+		plat_data->output_port = 1;
+	}
+
 	hdmi->hdmi = dw_hdmi_bind(pdev, encoder, plat_data, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 
 	/*
-- 
2.34.1

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

[Luca Ceresoli]

Hello Damon,

On Fri Apr 3, 2026 at 9:00 AM CEST, Damon Ding wrote:
> 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@1) in device tree is not used
>
>  B. hdmi->plat_data->output_port = 1:
>     the HDMI output (port@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@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) =

My understanding is that a hdmi-connector node is required in DT when using
drm_bridge_connector and DRM_BRIDGE_ATTACH_NO_CONNECTOR. Among others, it
is necessary to expose the correct connector type instead of defaulting to
DRM_MODE_CONNECTOR_HDMIA.

@Dmitry, others, can you confirm or deny the above?

If I'm correct, then the right way to support
DRM_BRIDGE_ATTACH_NO_CONNECTOR here is adding an hdmi-connector node in DT,
perhaps reusing the device tree overlay I proposed in [0].

[0] https://lore.kernel.org/lkml/20260407-drm-lcdif-dbanc-v4-8-247a16e61ef9@bootlin.com/

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com