From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Wed, 26 Feb 2020 11:24:29 +0000 (+0200)
Subject: drm/bridge: Extend bridge API to disable connector creation
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a25b988ff83f3ca0d8f5acf855fb1717c1c61a69;p=linux.git

drm/bridge: Extend bridge API to disable connector creation

Most bridge drivers create a DRM connector to model the connector at the
output of the bridge. This model is historical and has worked pretty
well so far, but causes several issues:

- It prevents supporting more complex display pipelines where DRM
connector operations are split over multiple components. For instance a
pipeline with a bridge connected to the DDC signals to read EDID data,
and another one connected to the HPD signal to detect connection and
disconnection, will not be possible to support through this model.

- It requires every bridge driver to implement similar connector
handling code, resulting in code duplication.

- It assumes that a bridge will either be wired to a connector or to
another bridge, but doesn't support bridges that can be used in both
positions very well (although there is some ad-hoc support for this in
the analogix_dp bridge driver).

In order to solve these issues, ownership of the connector should be
moved to the display controller driver (where it can be implemented
using helpers provided by the core).

Extend the bridge API to allow disabling connector creation in bridge
drivers as a first step towards the new model. The new flags argument to
the bridge .attach() operation allows instructing the bridge driver to
skip creating a connector. Unconditionally set the new flags argument to
0 for now to keep the existing behaviour, and modify all existing bridge
drivers to return an error when connector creation is not requested as
they don't support this feature yet.

The change is based on the following semantic patch, with manual review
and edits.

@ rule1 @
identifier funcs;
identifier fn;
@@
 struct drm_bridge_funcs funcs = {
 	...,
 	.attach = fn
 };

@ depends on rule1 @
identifier rule1.fn;
identifier bridge;
statement S, S1;
@@
 int fn(
 	struct drm_bridge *bridge
+	, enum drm_bridge_attach_flags flags
 )
 {
 	... when != S
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	S1
 	...
 }

@ depends on rule1 @
identifier rule1.fn;
identifier bridge, flags;
expression E1, E2, E3;
@@
 int fn(
 	struct drm_bridge *bridge,
 	enum drm_bridge_attach_flags flags
 ) {
 <...
 drm_bridge_attach(E1, E2, E3
+	, flags
 )
 ...>
 }

@@
expression E1, E2, E3;
@@
 drm_bridge_attach(E1, E2, E3
+	, 0
 )

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-10-laurent.pinchart@ideasonboard.com
---

diff --git a/drivers/gpu/drm/arc/arcpgu_hdmi.c b/drivers/gpu/drm/arc/arcpgu_hdmi.c
index 8fd7094beecef..52839934f2fb5 100644
--- a/drivers/gpu/drm/arc/arcpgu_hdmi.c
+++ b/drivers/gpu/drm/arc/arcpgu_hdmi.c
@@ -40,7 +40,7 @@ int arcpgu_drm_hdmi_init(struct drm_device *drm, struct device_node *np)
 		return ret;
 
 	/* Link drm_bridge to encoder */
-	ret = drm_bridge_attach(encoder, bridge, NULL);
+	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret)
 		drm_encoder_cleanup(encoder);
 
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
index 121b62682d803..e2019fe97fff5 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
@@ -114,7 +114,7 @@ static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
 	}
 
 	if (bridge) {
-		ret = drm_bridge_attach(&output->encoder, bridge, NULL);
+		ret = drm_bridge_attach(&output->encoder, bridge, NULL, 0);
 		if (!ret)
 			return 0;
 
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index a275e6c91bd7c..87b58c1acff4a 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -847,11 +847,17 @@ static void adv7511_bridge_mode_set(struct drm_bridge *bridge,
 	adv7511_mode_set(adv, mode, adj_mode);
 }
 
-static int adv7511_bridge_attach(struct drm_bridge *bridge)
+static int adv7511_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct adv7511 *adv = bridge_to_adv7511(bridge);
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
index 0d8d083b02074..5139c3724890e 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
@@ -520,11 +520,17 @@ static const struct drm_connector_funcs anx6345_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int anx6345_bridge_attach(struct drm_bridge *bridge)
+static int anx6345_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct anx6345 *anx6345 = bridge_to_anx6345(bridge);
 	int err;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
index 864423f59d660..0d5a5ad0c9ee4 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
@@ -886,11 +886,17 @@ static const struct drm_connector_funcs anx78xx_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int anx78xx_bridge_attach(struct drm_bridge *bridge)
+static int anx78xx_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct anx78xx *anx78xx = bridge_to_anx78xx(bridge);
 	int err;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index dfb59a5fefea0..9ded2cef57dd3 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1216,13 +1216,19 @@ static const struct drm_connector_funcs analogix_dp_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int analogix_dp_bridge_attach(struct drm_bridge *bridge)
+static int analogix_dp_bridge_attach(struct drm_bridge *bridge,
+				     enum drm_bridge_attach_flags flags)
 {
 	struct analogix_dp_device *dp = bridge->driver_private;
 	struct drm_encoder *encoder = dp->encoder;
 	struct drm_connector *connector = NULL;
 	int ret = 0;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
@@ -1598,7 +1604,7 @@ static int analogix_dp_create_bridge(struct drm_device *drm_dev,
 	bridge->driver_private = dp;
 	bridge->funcs = &analogix_dp_bridge_funcs;
 
-	ret = drm_bridge_attach(dp->encoder, bridge, NULL);
+	ret = drm_bridge_attach(dp->encoder, bridge, NULL, 0);
 	if (ret) {
 		DRM_ERROR("failed to attach drm bridge\n");
 		return -EINVAL;
diff --git a/drivers/gpu/drm/bridge/cdns-dsi.c b/drivers/gpu/drm/bridge/cdns-dsi.c
index b7c97f0602417..69c3892caee52 100644
--- a/drivers/gpu/drm/bridge/cdns-dsi.c
+++ b/drivers/gpu/drm/bridge/cdns-dsi.c
@@ -644,7 +644,8 @@ static int cdns_dsi_check_conf(struct cdns_dsi *dsi,
 	return 0;
 }
 
-static int cdns_dsi_bridge_attach(struct drm_bridge *bridge)
+static int cdns_dsi_bridge_attach(struct drm_bridge *bridge,
+				  enum drm_bridge_attach_flags flags)
 {
 	struct cdns_dsi_input *input = bridge_to_cdns_dsi_input(bridge);
 	struct cdns_dsi *dsi = input_to_dsi(input);
@@ -656,7 +657,8 @@ static int cdns_dsi_bridge_attach(struct drm_bridge *bridge)
 		return -ENOTSUPP;
 	}
 
-	return drm_bridge_attach(bridge->encoder, output->bridge, bridge);
+	return drm_bridge_attach(bridge->encoder, output->bridge, bridge,
+				 flags);
 }
 
 static enum drm_mode_status
diff --git a/drivers/gpu/drm/bridge/dumb-vga-dac.c b/drivers/gpu/drm/bridge/dumb-vga-dac.c
index cc33dc411b9e8..ad5b5a849e43c 100644
--- a/drivers/gpu/drm/bridge/dumb-vga-dac.c
+++ b/drivers/gpu/drm/bridge/dumb-vga-dac.c
@@ -100,11 +100,17 @@ static const struct drm_connector_funcs dumb_vga_con_funcs = {
 	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
 };
 
-static int dumb_vga_attach(struct drm_bridge *bridge)
+static int dumb_vga_attach(struct drm_bridge *bridge,
+			   enum drm_bridge_attach_flags flags)
 {
 	struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Missing encoder\n");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/lvds-codec.c b/drivers/gpu/drm/bridge/lvds-codec.c
index f7ae28ed1c141..24fb1befdfa2e 100644
--- a/drivers/gpu/drm/bridge/lvds-codec.c
+++ b/drivers/gpu/drm/bridge/lvds-codec.c
@@ -26,12 +26,13 @@ static inline struct lvds_codec *to_lvds_codec(struct drm_bridge *bridge)
 	return container_of(bridge, struct lvds_codec, bridge);
 }
 
-static int lvds_codec_attach(struct drm_bridge *bridge)
+static int lvds_codec_attach(struct drm_bridge *bridge,
+			     enum drm_bridge_attach_flags flags)
 {
 	struct lvds_codec *lvds_codec = to_lvds_codec(bridge);
 
 	return drm_bridge_attach(bridge->encoder, lvds_codec->panel_bridge,
-				 bridge);
+				 bridge, flags);
 }
 
 static void lvds_codec_enable(struct drm_bridge *bridge)
diff --git a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
index e8a49f6146c61..6200f12a37e69 100644
--- a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
+++ b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
@@ -206,13 +206,19 @@ static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int ge_b850v3_lvds_attach(struct drm_bridge *bridge)
+static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
 	struct i2c_client *stdp4028_i2c
 			= ge_b850v3_lvds_ptr->stdp4028_i2c;
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/nxp-ptn3460.c b/drivers/gpu/drm/bridge/nxp-ptn3460.c
index 57ff013395597..438e566ce0a4a 100644
--- a/drivers/gpu/drm/bridge/nxp-ptn3460.c
+++ b/drivers/gpu/drm/bridge/nxp-ptn3460.c
@@ -236,11 +236,17 @@ static const struct drm_connector_funcs ptn3460_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int ptn3460_bridge_attach(struct drm_bridge *bridge)
+static int ptn3460_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct ptn3460_bridge *ptn_bridge = bridge_to_ptn3460(bridge);
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index 9660736ddbf36..5c92d7c9fd616 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -53,12 +53,18 @@ static const struct drm_connector_funcs panel_bridge_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int panel_bridge_attach(struct drm_bridge *bridge)
+static int panel_bridge_attach(struct drm_bridge *bridge,
+			       enum drm_bridge_attach_flags flags)
 {
 	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
 	struct drm_connector *connector = &panel_bridge->connector;
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Missing encoder\n");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/parade-ps8622.c b/drivers/gpu/drm/bridge/parade-ps8622.c
index 10c47c008b401..d789ea2a7fb9e 100644
--- a/drivers/gpu/drm/bridge/parade-ps8622.c
+++ b/drivers/gpu/drm/bridge/parade-ps8622.c
@@ -476,11 +476,17 @@ static const struct drm_connector_funcs ps8622_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int ps8622_attach(struct drm_bridge *bridge)
+static int ps8622_attach(struct drm_bridge *bridge,
+			 enum drm_bridge_attach_flags flags)
 {
 	struct ps8622_bridge *ps8622 = bridge_to_ps8622(bridge);
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		DRM_ERROR("Parent encoder object not found");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
index c6c06688aff23..d3a53442d449a 100644
--- a/drivers/gpu/drm/bridge/parade-ps8640.c
+++ b/drivers/gpu/drm/bridge/parade-ps8640.c
@@ -187,7 +187,8 @@ static void ps8640_post_disable(struct drm_bridge *bridge)
 		DRM_ERROR("cannot disable regulators %d\n", ret);
 }
 
-static int ps8640_bridge_attach(struct drm_bridge *bridge)
+static int ps8640_bridge_attach(struct drm_bridge *bridge,
+				enum drm_bridge_attach_flags flags)
 {
 	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
 	struct device *dev = &ps_bridge->page[0]->dev;
@@ -234,7 +235,7 @@ static int ps8640_bridge_attach(struct drm_bridge *bridge)
 
 	/* Attach the panel-bridge to the dsi bridge */
 	return drm_bridge_attach(bridge->encoder, ps_bridge->panel_bridge,
-				 &ps_bridge->bridge);
+				 &ps_bridge->bridge, flags);
 
 err_dsi_attach:
 	mipi_dsi_device_unregister(dsi);
diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
index b70e8c5cf2e13..6dad025f8da7d 100644
--- a/drivers/gpu/drm/bridge/sii902x.c
+++ b/drivers/gpu/drm/bridge/sii902x.c
@@ -399,12 +399,18 @@ out:
 	mutex_unlock(&sii902x->mutex);
 }
 
-static int sii902x_bridge_attach(struct drm_bridge *bridge)
+static int sii902x_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct sii902x *sii902x = bridge_to_sii902x(bridge);
 	struct drm_device *drm = bridge->dev;
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	drm_connector_helper_add(&sii902x->connector,
 				 &sii902x_connector_helper_funcs);
 
diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
index 4c0eef406eb1f..92acd336aa894 100644
--- a/drivers/gpu/drm/bridge/sil-sii8620.c
+++ b/drivers/gpu/drm/bridge/sil-sii8620.c
@@ -2202,7 +2202,8 @@ static inline struct sii8620 *bridge_to_sii8620(struct drm_bridge *bridge)
 	return container_of(bridge, struct sii8620, bridge);
 }
 
-static int sii8620_attach(struct drm_bridge *bridge)
+static int sii8620_attach(struct drm_bridge *bridge,
+			  enum drm_bridge_attach_flags flags)
 {
 	struct sii8620 *ctx = bridge_to_sii8620(bridge);
 
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 67fca439bbfb4..9bad194cfd0ae 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2371,7 +2371,8 @@ static const struct drm_connector_helper_funcs dw_hdmi_connector_helper_funcs =
 	.atomic_check = dw_hdmi_connector_atomic_check,
 };
 
-static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
+static int dw_hdmi_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct dw_hdmi *hdmi = bridge->driver_private;
 	struct drm_encoder *encoder = bridge->encoder;
@@ -2379,6 +2380,11 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
 	struct cec_connector_info conn_info;
 	struct cec_notifier *notifier;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	connector->interlace_allowed = 1;
 	connector->polled = DRM_CONNECTOR_POLL_HPD;
 
@@ -3076,7 +3082,7 @@ struct dw_hdmi *dw_hdmi_bind(struct platform_device *pdev,
 	if (IS_ERR(hdmi))
 		return hdmi;
 
-	ret = drm_bridge_attach(encoder, &hdmi->bridge, NULL);
+	ret = drm_bridge_attach(encoder, &hdmi->bridge, NULL, 0);
 	if (ret) {
 		dw_hdmi_remove(hdmi);
 		DRM_ERROR("Failed to initialize bridge with drm\n");
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index 12823ae91065c..5ef0f154aa7bd 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
@@ -936,7 +936,8 @@ dw_mipi_dsi_bridge_mode_valid(struct drm_bridge *bridge,
 	return mode_status;
 }
 
-static int dw_mipi_dsi_bridge_attach(struct drm_bridge *bridge)
+static int dw_mipi_dsi_bridge_attach(struct drm_bridge *bridge,
+				     enum drm_bridge_attach_flags flags)
 {
 	struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
 
@@ -949,7 +950,8 @@ static int dw_mipi_dsi_bridge_attach(struct drm_bridge *bridge)
 	bridge->encoder->encoder_type = DRM_MODE_ENCODER_DSI;
 
 	/* Attach the panel-bridge to the dsi bridge */
-	return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge);
+	return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, bridge,
+				 flags);
 }
 
 static const struct drm_bridge_funcs dw_mipi_dsi_bridge_funcs = {
@@ -1120,7 +1122,7 @@ int dw_mipi_dsi_bind(struct dw_mipi_dsi *dsi, struct drm_encoder *encoder)
 {
 	int ret;
 
-	ret = drm_bridge_attach(encoder, &dsi->bridge, NULL);
+	ret = drm_bridge_attach(encoder, &dsi->bridge, NULL, 0);
 	if (ret) {
 		DRM_ERROR("Failed to initialize bridge with drm\n");
 		return ret;
diff --git a/drivers/gpu/drm/bridge/tc358764.c b/drivers/gpu/drm/bridge/tc358764.c
index 96207fcfde19b..283e4a8dd923e 100644
--- a/drivers/gpu/drm/bridge/tc358764.c
+++ b/drivers/gpu/drm/bridge/tc358764.c
@@ -349,12 +349,18 @@ static void tc358764_enable(struct drm_bridge *bridge)
 		dev_err(ctx->dev, "error enabling panel (%d)\n", ret);
 }
 
-static int tc358764_attach(struct drm_bridge *bridge)
+static int tc358764_attach(struct drm_bridge *bridge,
+			   enum drm_bridge_attach_flags flags)
 {
 	struct tc358764 *ctx = bridge_to_tc358764(bridge);
 	struct drm_device *drm = bridge->dev;
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	ctx->connector.polled = DRM_CONNECTOR_POLL_HPD;
 	ret = drm_connector_init(drm, &ctx->connector,
 				 &tc358764_connector_funcs,
diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index 3709e5ace7246..402a690d1fe56 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -31,6 +31,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
+#include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 
 /* Registers */
@@ -1403,13 +1404,19 @@ static const struct drm_connector_funcs tc_connector_funcs = {
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 };
 
-static int tc_bridge_attach(struct drm_bridge *bridge)
+static int tc_bridge_attach(struct drm_bridge *bridge,
+			    enum drm_bridge_attach_flags flags)
 {
 	u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
 	struct tc_data *tc = bridge_to_tc(bridge);
 	struct drm_device *drm = bridge->dev;
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	/* Create DP/eDP connector */
 	drm_connector_helper_add(&tc->connector, &tc_connector_helper_funcs);
 	ret = drm_connector_init(drm, &tc->connector, &tc_connector_funcs,
diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
index da7af03256f66..1b39e8d37834a 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -511,7 +511,8 @@ static const struct mipi_dsi_host_ops tc358768_dsi_host_ops = {
 	.transfer = tc358768_dsi_host_transfer,
 };
 
-static int tc358768_bridge_attach(struct drm_bridge *bridge)
+static int tc358768_bridge_attach(struct drm_bridge *bridge,
+				  enum drm_bridge_attach_flags flags)
 {
 	struct tc358768_priv *priv = bridge_to_tc358768(bridge);
 
@@ -520,7 +521,8 @@ static int tc358768_bridge_attach(struct drm_bridge *bridge)
 		return -ENOTSUPP;
 	}
 
-	return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge);
+	return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge,
+				 flags);
 }
 
 static enum drm_mode_status
diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
index 3d74129b29950..97d8129760e97 100644
--- a/drivers/gpu/drm/bridge/thc63lvd1024.c
+++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
@@ -42,11 +42,12 @@ static inline struct thc63_dev *to_thc63(struct drm_bridge *bridge)
 	return container_of(bridge, struct thc63_dev, bridge);
 }
 
-static int thc63_attach(struct drm_bridge *bridge)
+static int thc63_attach(struct drm_bridge *bridge,
+			enum drm_bridge_attach_flags flags)
 {
 	struct thc63_dev *thc63 = to_thc63(bridge);
 
-	return drm_bridge_attach(bridge->encoder, thc63->next, bridge);
+	return drm_bridge_attach(bridge->encoder, thc63->next, bridge, flags);
 }
 
 static enum drm_mode_status thc63_mode_valid(struct drm_bridge *bridge,
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 6ce60a64b6035..6ad688b320aee 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -266,7 +266,8 @@ static int ti_sn_bridge_parse_regulators(struct ti_sn_bridge *pdata)
 				       pdata->supplies);
 }
 
-static int ti_sn_bridge_attach(struct drm_bridge *bridge)
+static int ti_sn_bridge_attach(struct drm_bridge *bridge,
+			       enum drm_bridge_attach_flags flags)
 {
 	int ret, val;
 	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
@@ -277,6 +278,11 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge)
 						   .node = NULL,
 						 };
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	ret = drm_connector_init(bridge->dev, &pdata->connector,
 				 &ti_sn_bridge_connector_funcs,
 				 DRM_MODE_CONNECTOR_eDP);
diff --git a/drivers/gpu/drm/bridge/ti-tfp410.c b/drivers/gpu/drm/bridge/ti-tfp410.c
index 108e8cd7ab688..193c9368f6643 100644
--- a/drivers/gpu/drm/bridge/ti-tfp410.c
+++ b/drivers/gpu/drm/bridge/ti-tfp410.c
@@ -118,11 +118,17 @@ static const struct drm_connector_funcs tfp410_con_funcs = {
 	.atomic_destroy_state	= drm_atomic_helper_connector_destroy_state,
 };
 
-static int tfp410_attach(struct drm_bridge *bridge)
+static int tfp410_attach(struct drm_bridge *bridge,
+			 enum drm_bridge_attach_flags flags)
 {
 	struct tfp410 *dvi = drm_bridge_to_tfp410(bridge);
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	if (!bridge->encoder) {
 		dev_err(dvi->dev, "Missing encoder\n");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 5a8f7d7e05f3b..96eace94fea85 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -149,6 +149,7 @@ static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
  * @encoder: DRM encoder
  * @bridge: bridge to attach
  * @previous: previous bridge in the chain (optional)
+ * @flags: DRM_BRIDGE_ATTACH_* flags
  *
  * Called by a kms driver to link the bridge to an encoder's chain. The previous
  * argument specifies the previous bridge in the chain. If NULL, the bridge is
@@ -166,7 +167,8 @@ static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
  * Zero on success, error code on failure
  */
 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
-		      struct drm_bridge *previous)
+		      struct drm_bridge *previous,
+		      enum drm_bridge_attach_flags flags)
 {
 	int ret;
 
@@ -188,7 +190,7 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 		list_add(&bridge->chain_node, &encoder->bridge_chain);
 
 	if (bridge->funcs->attach) {
-		ret = bridge->funcs->attach(bridge);
+		ret = bridge->funcs->attach(bridge, flags);
 		if (ret < 0)
 			goto err_reset_bridge;
 	}
@@ -312,6 +314,20 @@ void drm_bridge_detach(struct drm_bridge *bridge)
  *   allows providing a single static const &drm_bridge_funcs instance in
  *   bridge drivers, improving security by storing function pointers in
  *   read-only memory.
+ *
+ *   In order to ease transition, bridge drivers may support both the old and
+ *   new models by making connector creation optional and implementing the
+ *   connected-related bridge operations. Connector creation is then controlled
+ *   by the flags argument to the drm_bridge_attach() function. Display drivers
+ *   that support the new model and create connectors themselves shall set the
+ *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
+ *   connector creation. For intermediate bridges in the chain, the flag shall
+ *   be passed to the drm_bridge_attach() call for the downstream bridge.
+ *   Bridge drivers that implement the new model only shall return an error
+ *   from their &drm_bridge_funcs.attach handler when the
+ *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
+ *   should use the new model, and convert the bridge drivers they use if
+ *   needed, in order to gradually transition to the new model.
  */
 
 /**
diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index 15fb516ae2d82..8ff4504161d53 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -229,7 +229,7 @@ static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
 int drm_simple_display_pipe_attach_bridge(struct drm_simple_display_pipe *pipe,
 					  struct drm_bridge *bridge)
 {
-	return drm_bridge_attach(&pipe->encoder, bridge, NULL);
+	return drm_bridge_attach(&pipe->encoder, bridge, NULL, 0);
 }
 EXPORT_SYMBOL(drm_simple_display_pipe_attach_bridge);
 
diff --git a/drivers/gpu/drm/exynos/exynos_dp.c b/drivers/gpu/drm/exynos/exynos_dp.c
index 4785885c0f4f9..d23d3502ca919 100644
--- a/drivers/gpu/drm/exynos/exynos_dp.c
+++ b/drivers/gpu/drm/exynos/exynos_dp.c
@@ -106,7 +106,8 @@ static int exynos_dp_bridge_attach(struct analogix_dp_plat_data *plat_data,
 
 	/* Pre-empt DP connector creation if there's a bridge */
 	if (dp->ptn_bridge) {
-		ret = drm_bridge_attach(&dp->encoder, dp->ptn_bridge, bridge);
+		ret = drm_bridge_attach(&dp->encoder, dp->ptn_bridge, bridge,
+					0);
 		if (ret) {
 			DRM_DEV_ERROR(dp->dev,
 				      "Failed to attach bridge to drm\n");
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 33628d85edad9..669d3857502a9 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -1540,7 +1540,7 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
 
 	out_bridge  = of_drm_find_bridge(device->dev.of_node);
 	if (out_bridge) {
-		drm_bridge_attach(encoder, out_bridge, NULL);
+		drm_bridge_attach(encoder, out_bridge, NULL, 0);
 		dsi->out_bridge = out_bridge;
 		list_splice_init(&encoder->bridge_chain, &dsi->bridge_chain);
 	} else {
@@ -1717,7 +1717,7 @@ static int exynos_dsi_bind(struct device *dev, struct device *master,
 	if (dsi->in_bridge_node) {
 		in_bridge = of_drm_find_bridge(dsi->in_bridge_node);
 		if (in_bridge)
-			drm_bridge_attach(encoder, in_bridge, NULL);
+			drm_bridge_attach(encoder, in_bridge, NULL, 0);
 	}
 
 	return mipi_dsi_host_register(&dsi->dsi_host);
diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
index 9ff921f43a939..3e5f1a77286d9 100644
--- a/drivers/gpu/drm/exynos/exynos_hdmi.c
+++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
@@ -960,7 +960,7 @@ static int hdmi_create_connector(struct drm_encoder *encoder)
 	drm_connector_attach_encoder(connector, encoder);
 
 	if (hdata->bridge) {
-		ret = drm_bridge_attach(encoder, hdata->bridge, NULL);
+		ret = drm_bridge_attach(encoder, hdata->bridge, NULL, 0);
 		if (ret)
 			DRM_DEV_ERROR(hdata->dev, "Failed to attach bridge\n");
 	}
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
index 9598ee3cc4d29..cff344367f81f 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
@@ -151,5 +151,5 @@ int fsl_dcu_create_outputs(struct fsl_dcu_drm_device *fsl_dev)
 		return fsl_dcu_attach_panel(fsl_dev, panel);
 	}
 
-	return drm_bridge_attach(&fsl_dev->encoder, bridge, NULL);
+	return drm_bridge_attach(&fsl_dev->encoder, bridge, NULL, 0);
 }
diff --git a/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c b/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c
index bdcf9c6ae9e9e..f31068d74b18f 100644
--- a/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c
+++ b/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c
@@ -777,7 +777,7 @@ static int dsi_bridge_init(struct drm_device *dev, struct dw_dsi *dsi)
 	int ret;
 
 	/* associate the bridge to dsi encoder */
-	ret = drm_bridge_attach(encoder, bridge, NULL);
+	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret) {
 		DRM_ERROR("failed to attach external bridge\n");
 		return ret;
diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index a63790d32d752..c3332209f27a8 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -1356,10 +1356,16 @@ static int tda998x_connector_init(struct tda998x_priv *priv,
 
 /* DRM bridge functions */
 
-static int tda998x_bridge_attach(struct drm_bridge *bridge)
+static int tda998x_bridge_attach(struct drm_bridge *bridge,
+				 enum drm_bridge_attach_flags flags)
 {
 	struct tda998x_priv *priv = bridge_to_tda998x_priv(bridge);
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	return tda998x_connector_init(priv, bridge->dev);
 }
 
@@ -2022,7 +2028,7 @@ static int tda998x_encoder_init(struct device *dev, struct drm_device *drm)
 	if (ret)
 		goto err_encoder;
 
-	ret = drm_bridge_attach(&priv->encoder, &priv->bridge, NULL);
+	ret = drm_bridge_attach(&priv->encoder, &priv->bridge, NULL, 0);
 	if (ret)
 		goto err_bridge;
 
diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index 8cb2665b2c742..4da22a94790cf 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -446,7 +446,7 @@ static int imx_ldb_register(struct drm_device *drm,
 
 	if (imx_ldb_ch->bridge) {
 		ret = drm_bridge_attach(&imx_ldb_ch->encoder,
-					imx_ldb_ch->bridge, NULL);
+					imx_ldb_ch->bridge, NULL, 0);
 		if (ret) {
 			DRM_ERROR("Failed to initialize bridge with drm\n");
 			return ret;
diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
index 142acff5ab37b..08fafa4bf8c21 100644
--- a/drivers/gpu/drm/imx/parallel-display.c
+++ b/drivers/gpu/drm/imx/parallel-display.c
@@ -292,7 +292,7 @@ static int imx_pd_register(struct drm_device *drm,
 			 DRM_MODE_ENCODER_NONE, NULL);
 
 	imxpd->bridge.funcs = &imx_pd_bridge_funcs;
-	drm_bridge_attach(encoder, &imxpd->bridge, NULL);
+	drm_bridge_attach(encoder, &imxpd->bridge, NULL, 0);
 
 	if (!imxpd->next_bridge) {
 		drm_connector_helper_add(&imxpd->connector,
@@ -307,7 +307,7 @@ static int imx_pd_register(struct drm_device *drm,
 
 	if (imxpd->next_bridge) {
 		ret = drm_bridge_attach(encoder, imxpd->next_bridge,
-					&imxpd->bridge);
+					&imxpd->bridge, 0);
 		if (ret < 0) {
 			dev_err(imxpd->dev, "failed to attach bridge: %d\n",
 				ret);
diff --git a/drivers/gpu/drm/ingenic/ingenic-drm.c b/drivers/gpu/drm/ingenic/ingenic-drm.c
index 6d47ef7b148c3..9dfe7cb530e11 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm.c
@@ -737,7 +737,7 @@ static int ingenic_drm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = drm_bridge_attach(&priv->encoder, bridge, NULL);
+	ret = drm_bridge_attach(&priv->encoder, bridge, NULL, 0);
 	if (ret) {
 		dev_err(dev, "Unable to attach bridge");
 		return ret;
diff --git a/drivers/gpu/drm/mcde/mcde_dsi.c b/drivers/gpu/drm/mcde/mcde_dsi.c
index bb6528b01cd07..7af5ebb0c4368 100644
--- a/drivers/gpu/drm/mcde/mcde_dsi.c
+++ b/drivers/gpu/drm/mcde/mcde_dsi.c
@@ -986,7 +986,8 @@ static void mcde_dsi_bridge_disable(struct drm_bridge *bridge)
 	clk_disable_unprepare(d->lp_clk);
 }
 
-static int mcde_dsi_bridge_attach(struct drm_bridge *bridge)
+static int mcde_dsi_bridge_attach(struct drm_bridge *bridge,
+				  enum drm_bridge_attach_flags flags)
 {
 	struct mcde_dsi *d = bridge_to_mcde_dsi(bridge);
 	struct drm_device *drm = bridge->dev;
@@ -998,7 +999,7 @@ static int mcde_dsi_bridge_attach(struct drm_bridge *bridge)
 	}
 
 	/* Attach the DSI bridge to the output (panel etc) bridge */
-	ret = drm_bridge_attach(bridge->encoder, d->bridge_out, bridge);
+	ret = drm_bridge_attach(bridge->encoder, d->bridge_out, bridge, flags);
 	if (ret) {
 		dev_err(d->dev, "failed to attach the DSI bridge\n");
 		return ret;
diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
index 01fa8b8d763d1..14fbe1c09ce92 100644
--- a/drivers/gpu/drm/mediatek/mtk_dpi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
@@ -607,7 +607,7 @@ static int mtk_dpi_bind(struct device *dev, struct device *master, void *data)
 	/* Currently DPI0 is fixed to be driven by OVL1 */
 	dpi->encoder.possible_crtcs = BIT(1);
 
-	ret = drm_bridge_attach(&dpi->encoder, dpi->bridge, NULL);
+	ret = drm_bridge_attach(&dpi->encoder, dpi->bridge, NULL, 0);
 	if (ret) {
 		dev_err(dev, "Failed to attach bridge: %d\n", ret);
 		goto err_cleanup;
diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 5fa1073cf26b9..0ede69830a9dd 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -904,7 +904,7 @@ static int mtk_dsi_create_conn_enc(struct drm_device *drm, struct mtk_dsi *dsi)
 
 	/* If there's a bridge, attach to it and let it create the connector */
 	if (dsi->bridge) {
-		ret = drm_bridge_attach(&dsi->encoder, dsi->bridge, NULL);
+		ret = drm_bridge_attach(&dsi->encoder, dsi->bridge, NULL, 0);
 		if (ret) {
 			DRM_ERROR("Failed to attach bridge to drm\n");
 			goto err_encoder_cleanup;
diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
index 5e4a4dbda443f..a8b20557539b9 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
@@ -1297,11 +1297,17 @@ static void mtk_hdmi_hpd_event(bool hpd, struct device *dev)
  * Bridge callbacks
  */
 
-static int mtk_hdmi_bridge_attach(struct drm_bridge *bridge)
+static int mtk_hdmi_bridge_attach(struct drm_bridge *bridge,
+				  enum drm_bridge_attach_flags flags)
 {
 	struct mtk_hdmi *hdmi = hdmi_ctx_from_bridge(bridge);
 	int ret;
 
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
+
 	ret = drm_connector_init_with_ddc(bridge->encoder->dev, &hdmi->conn,
 					  &mtk_hdmi_connector_funcs,
 					  DRM_MODE_CONNECTOR_HDMIA,
@@ -1326,7 +1332,7 @@ static int mtk_hdmi_bridge_attach(struct drm_bridge *bridge)
 
 	if (hdmi->next_bridge) {
 		ret = drm_bridge_attach(bridge->encoder, hdmi->next_bridge,
-					bridge);
+					bridge, flags);
 		if (ret) {
 			dev_err(hdmi->dev,
 				"Failed to attach external bridge: %d\n", ret);
diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
index 104115d112eba..6af26ab5b09da 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
@@ -684,7 +684,7 @@ struct drm_bridge *msm_dsi_manager_bridge_init(u8 id)
 	bridge = &dsi_bridge->base;
 	bridge->funcs = &dsi_mgr_bridge_funcs;
 
-	ret = drm_bridge_attach(encoder, bridge, NULL);
+	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret)
 		goto fail;
 
@@ -713,7 +713,7 @@ struct drm_connector *msm_dsi_manager_ext_bridge_init(u8 id)
 	encoder = msm_dsi->encoder;
 
 	/* link the internal dsi bridge to the external bridge */
-	drm_bridge_attach(encoder, ext_bridge, int_bridge);
+	drm_bridge_attach(encoder, ext_bridge, int_bridge, 0);
 
 	/*
 	 * we need the drm_connector created by the external bridge
diff --git a/drivers/gpu/drm/msm/edp/edp.c b/drivers/gpu/drm/msm/edp/edp.c
index ad4e963ccd9b0..a78d6077802b6 100644
--- a/drivers/gpu/drm/msm/edp/edp.c
+++ b/drivers/gpu/drm/msm/edp/edp.c
@@ -178,7 +178,7 @@ int msm_edp_modeset_init(struct msm_edp *edp, struct drm_device *dev,
 		goto fail;
 	}
 
-	ret = drm_bridge_attach(encoder, edp->bridge, NULL);
+	ret = drm_bridge_attach(encoder, edp->bridge, NULL, 0);
 	if (ret)
 		goto fail;
 
diff --git a/drivers/gpu/drm/msm/edp/edp_bridge.c b/drivers/gpu/drm/msm/edp/edp_bridge.c
index b65b5cc2dba2d..c69a37e0c7082 100644
--- a/drivers/gpu/drm/msm/edp/edp_bridge.c
+++ b/drivers/gpu/drm/msm/edp/edp_bridge.c
@@ -97,7 +97,7 @@ struct drm_bridge *msm_edp_bridge_init(struct msm_edp *edp)
 	bridge = &edp_bridge->base;
 	bridge->funcs = &edp_bridge_funcs;
 
-	ret = drm_bridge_attach(edp->encoder, bridge, NULL);
+	ret = drm_bridge_attach(edp->encoder, bridge, NULL, 0);
 	if (ret)
 		goto fail;
 
diff --git a/drivers/gpu/drm/msm/hdmi/hdmi.c b/drivers/gpu/drm/msm/hdmi/hdmi.c
index 1a9b6289637da..3a8646535c14c 100644
--- a/drivers/gpu/drm/msm/hdmi/hdmi.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi.c
@@ -327,7 +327,7 @@ int msm_hdmi_modeset_init(struct hdmi *hdmi,
 		goto fail;
 	}
 
-	ret = drm_bridge_attach(encoder, hdmi->bridge, NULL);
+	ret = drm_bridge_attach(encoder, hdmi->bridge, NULL, 0);
 	if (ret)
 		goto fail;
 
diff --git a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
index ba81338a9bf84..6e380db9287ba 100644
--- a/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi_bridge.c
@@ -287,7 +287,7 @@ struct drm_bridge *msm_hdmi_bridge_init(struct hdmi *hdmi)
 	bridge = &hdmi_bridge->base;
 	bridge->funcs = &msm_hdmi_bridge_funcs;
 
-	ret = drm_bridge_attach(hdmi->encoder, bridge, NULL);
+	ret = drm_bridge_attach(hdmi->encoder, bridge, NULL, 0);
 	if (ret)
 		goto fail;
 
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index d2750f60f5192..390e0662a8b87 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -297,7 +297,7 @@ static int omap_modeset_init(struct drm_device *dev)
 
 		if (pipe->output->bridge) {
 			ret = drm_bridge_attach(pipe->encoder,
-						pipe->output->bridge, NULL);
+						pipe->output->bridge, NULL, 0);
 			if (ret < 0)
 				return ret;
 		}
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
index 3cd83a030a04f..c07c6a88aff02 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
@@ -121,7 +121,7 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
 	 * Attach the bridge to the encoder. The bridge will create the
 	 * connector.
 	 */
-	ret = drm_bridge_attach(encoder, bridge, NULL);
+	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret) {
 		drm_encoder_cleanup(encoder);
 		return ret;
diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
index 06432c881e07a..ab0d49618cf90 100644
--- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
+++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
@@ -23,6 +23,7 @@
 #include <drm/drm_bridge.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
+#include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 
 #include "rcar_lvds.h"
@@ -643,7 +644,8 @@ static bool rcar_lvds_mode_fixup(struct drm_bridge *bridge,
 	return true;
 }
 
-static int rcar_lvds_attach(struct drm_bridge *bridge)
+static int rcar_lvds_attach(struct drm_bridge *bridge,
+			    enum drm_bridge_attach_flags flags)
 {
 	struct rcar_lvds *lvds = bridge_to_rcar_lvds(bridge);
 	struct drm_connector *connector = &lvds->connector;
@@ -653,7 +655,12 @@ static int rcar_lvds_attach(struct drm_bridge *bridge)
 	/* If we have a next bridge just attach it. */
 	if (lvds->next_bridge)
 		return drm_bridge_attach(bridge->encoder, lvds->next_bridge,
-					 bridge);
+					 bridge, flags);
+
+	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
+		DRM_ERROR("Fix bridge driver to make connector optional!");
+		return -EINVAL;
+	}
 
 	/* Otherwise if we have a panel, create a connector. */
 	if (!lvds->panel)
diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c
index f25a36743cbde..449a62908d213 100644
--- a/drivers/gpu/drm/rockchip/rockchip_lvds.c
+++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c
@@ -646,7 +646,7 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master,
 			goto err_free_connector;
 		}
 	} else {
-		ret = drm_bridge_attach(encoder, lvds->bridge, NULL);
+		ret = drm_bridge_attach(encoder, lvds->bridge, NULL, 0);
 		if (ret) {
 			DRM_DEV_ERROR(drm_dev->dev,
 				      "failed to attach bridge: %d\n", ret);
diff --git a/drivers/gpu/drm/rockchip/rockchip_rgb.c b/drivers/gpu/drm/rockchip/rockchip_rgb.c
index ae730275a34f8..3e24849859553 100644
--- a/drivers/gpu/drm/rockchip/rockchip_rgb.c
+++ b/drivers/gpu/drm/rockchip/rockchip_rgb.c
@@ -144,7 +144,7 @@ struct rockchip_rgb *rockchip_rgb_init(struct device *dev,
 
 	rgb->bridge = bridge;
 
-	ret = drm_bridge_attach(encoder, rgb->bridge, NULL);
+	ret = drm_bridge_attach(encoder, rgb->bridge, NULL, 0);
 	if (ret) {
 		DRM_DEV_ERROR(drm_dev->dev,
 			      "failed to attach bridge: %d\n", ret);
diff --git a/drivers/gpu/drm/sti/sti_dvo.c b/drivers/gpu/drm/sti/sti_dvo.c
index b2778ec1cdd79..3d04bfca21a06 100644
--- a/drivers/gpu/drm/sti/sti_dvo.c
+++ b/drivers/gpu/drm/sti/sti_dvo.c
@@ -467,7 +467,7 @@ static int sti_dvo_bind(struct device *dev, struct device *master, void *data)
 	bridge->of_node = dvo->dev.of_node;
 	drm_bridge_add(bridge);
 
-	err = drm_bridge_attach(encoder, bridge, NULL);
+	err = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (err) {
 		DRM_ERROR("Failed to attach bridge\n");
 		return err;
diff --git a/drivers/gpu/drm/sti/sti_hda.c b/drivers/gpu/drm/sti/sti_hda.c
index 2bb32009d117a..f3f28d79b0e40 100644
--- a/drivers/gpu/drm/sti/sti_hda.c
+++ b/drivers/gpu/drm/sti/sti_hda.c
@@ -701,7 +701,7 @@ static int sti_hda_bind(struct device *dev, struct device *master, void *data)
 
 	bridge->driver_private = hda;
 	bridge->funcs = &sti_hda_bridge_funcs;
-	drm_bridge_attach(encoder, bridge, NULL);
+	drm_bridge_attach(encoder, bridge, NULL, 0);
 
 	connector->encoder = encoder;
 
diff --git a/drivers/gpu/drm/sti/sti_hdmi.c b/drivers/gpu/drm/sti/sti_hdmi.c
index 64ed102033c8b..18eaf786ffa46 100644
--- a/drivers/gpu/drm/sti/sti_hdmi.c
+++ b/drivers/gpu/drm/sti/sti_hdmi.c
@@ -1281,7 +1281,7 @@ static int sti_hdmi_bind(struct device *dev, struct device *master, void *data)
 
 	bridge->driver_private = hdmi;
 	bridge->funcs = &sti_hdmi_bridge_funcs;
-	drm_bridge_attach(encoder, bridge, NULL);
+	drm_bridge_attach(encoder, bridge, NULL, 0);
 
 	connector->encoder = encoder;
 
diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 99bf93e8b36f0..df585fe64f614 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1109,7 +1109,7 @@ static int ltdc_encoder_init(struct drm_device *ddev, struct drm_bridge *bridge)
 
 	drm_encoder_helper_add(encoder, &ltdc_encoder_helper_funcs);
 
-	ret = drm_bridge_attach(encoder, bridge, NULL);
+	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 	if (ret) {
 		drm_encoder_cleanup(encoder);
 		return -EINVAL;
diff --git a/drivers/gpu/drm/sun4i/sun4i_lvds.c b/drivers/gpu/drm/sun4i/sun4i_lvds.c
index 65b7a87396667..26e5c7ceb8ffd 100644
--- a/drivers/gpu/drm/sun4i/sun4i_lvds.c
+++ b/drivers/gpu/drm/sun4i/sun4i_lvds.c
@@ -156,7 +156,7 @@ int sun4i_lvds_init(struct drm_device *drm, struct sun4i_tcon *tcon)
 	}
 
 	if (bridge) {
-		ret = drm_bridge_attach(encoder, bridge, NULL);
+		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 		if (ret) {
 			dev_err(drm->dev, "Couldn't attach our bridge\n");
 			goto err_cleanup_connector;
diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c b/drivers/gpu/drm/sun4i/sun4i_rgb.c
index b27f16af50f5d..3b23d5be3cf3b 100644
--- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
+++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
@@ -253,7 +253,7 @@ int sun4i_rgb_init(struct drm_device *drm, struct sun4i_tcon *tcon)
 	}
 
 	if (rgb->bridge) {
-		ret = drm_bridge_attach(encoder, rgb->bridge, NULL);
+		ret = drm_bridge_attach(encoder, rgb->bridge, NULL, 0);
 		if (ret) {
 			dev_err(drm->dev, "Couldn't attach our bridge\n");
 			goto err_cleanup_connector;
diff --git a/drivers/gpu/drm/tidss/tidss_kms.c b/drivers/gpu/drm/tidss/tidss_kms.c
index 5311e0f1c5515..3b6f8d54a0167 100644
--- a/drivers/gpu/drm/tidss/tidss_kms.c
+++ b/drivers/gpu/drm/tidss/tidss_kms.c
@@ -172,7 +172,7 @@ static int tidss_dispc_modeset_init(struct tidss_device *tidss)
 			return PTR_ERR(enc);
 		}
 
-		ret = drm_bridge_attach(enc, pipes[i].bridge, NULL);
+		ret = drm_bridge_attach(enc, pipes[i].bridge, NULL, 0);
 		if (ret) {
 			dev_err(tidss->dev, "bridge attach failed: %d\n", ret);
 			return ret;
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_external.c b/drivers/gpu/drm/tilcdc/tilcdc_external.c
index 51d034e095f4d..28b7f703236e8 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_external.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_external.c
@@ -95,7 +95,7 @@ int tilcdc_attach_bridge(struct drm_device *ddev, struct drm_bridge *bridge)
 
 	priv->external_encoder->possible_crtcs = BIT(0);
 
-	ret = drm_bridge_attach(priv->external_encoder, bridge, NULL);
+	ret = drm_bridge_attach(priv->external_encoder, bridge, NULL, 0);
 	if (ret) {
 		dev_err(ddev->dev, "drm_bridge_attach() failed %d\n", ret);
 		return ret;
diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c
index c586325de2a5b..6dfede03396ef 100644
--- a/drivers/gpu/drm/vc4/vc4_dpi.c
+++ b/drivers/gpu/drm/vc4/vc4_dpi.c
@@ -252,7 +252,7 @@ static int vc4_dpi_init_bridge(struct vc4_dpi *dpi)
 		bridge = drm_panel_bridge_add_typed(panel,
 						    DRM_MODE_CONNECTOR_DPI);
 
-	return drm_bridge_attach(dpi->encoder, bridge, NULL);
+	return drm_bridge_attach(dpi->encoder, bridge, NULL, 0);
 }
 
 static int vc4_dpi_bind(struct device *dev, struct device *master, void *data)
diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index fd8a2eb605053..d99b1d5266517 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -1619,7 +1619,7 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
 			 DRM_MODE_ENCODER_DSI, NULL);
 	drm_encoder_helper_add(dsi->encoder, &vc4_dsi_encoder_helper_funcs);
 
-	ret = drm_bridge_attach(dsi->encoder, dsi->bridge, NULL);
+	ret = drm_bridge_attach(dsi->encoder, dsi->bridge, NULL, 0);
 	if (ret) {
 		dev_err(dev, "bridge attach failed: %d\n", ret);
 		return ret;
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 018e195c48083..ea2aa5ebae346 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -39,6 +39,17 @@ struct drm_panel;
 struct edid;
 struct i2c_adapter;
 
+/**
+ * enum drm_bridge_attach_flags - Flags for &drm_bridge_funcs.attach
+ */
+enum drm_bridge_attach_flags {
+	/**
+	 * @DRM_BRIDGE_ATTACH_NO_CONNECTOR: When this flag is set the bridge
+	 * shall not create a drm_connector.
+	 */
+	DRM_BRIDGE_ATTACH_NO_CONNECTOR = BIT(0),
+};
+
 /**
  * struct drm_bridge_funcs - drm_bridge control functions
  */
@@ -47,7 +58,8 @@ struct drm_bridge_funcs {
 	 * @attach:
 	 *
 	 * This callback is invoked whenever our bridge is being attached to a
-	 * &drm_encoder.
+	 * &drm_encoder. The flags argument tunes the behaviour of the attach
+	 * operation (see DRM_BRIDGE_ATTACH_*).
 	 *
 	 * The @attach callback is optional.
 	 *
@@ -55,7 +67,8 @@ struct drm_bridge_funcs {
 	 *
 	 * Zero on success, error code on failure.
 	 */
-	int (*attach)(struct drm_bridge *bridge);
+	int (*attach)(struct drm_bridge *bridge,
+		      enum drm_bridge_attach_flags flags);
 
 	/**
 	 * @detach:
@@ -757,7 +770,8 @@ void drm_bridge_add(struct drm_bridge *bridge);
 void drm_bridge_remove(struct drm_bridge *bridge);
 struct drm_bridge *of_drm_find_bridge(struct device_node *np);
 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
-		      struct drm_bridge *previous);
+		      struct drm_bridge *previous,
+		      enum drm_bridge_attach_flags flags);
 
 /**
  * drm_bridge_get_next_bridge() - Get the next bridge in the chain