linux-kernel - [PATCH v4 25/25] rm/tilcdc: Add support for DRM_BRIDGE_ATTACH_NO

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Message-Id: <20260116-feature_tilcdc-v4-25-2c1c22143087@bootlin.com>
Date: Fri, 16 Jan 2026 18:02:25 +0100
From: "Kory Maincent (TI.com)" <kory.maincent@...tlin.com>
To: Jyri Sarha <jyri.sarha@....fi>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Russell King <linux@...linux.org.uk>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Tony Lindgren <tony@...mide.com>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>
Cc: Markus Schneider-Pargmann <msp@...libre.com>, 
 Bajjuri Praneeth <praneeth@...com>, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>, 
 Louis Chauvet <louis.chauvet@...tlin.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Miguel Gazquez <miguel.gazquez@...tlin.com>, 
 Herve Codina <herve.codina@...tlin.com>, dri-devel@...ts.freedesktop.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org, 
 "Kory Maincent (TI.com)" <kory.maincent@...tlin.com>
Subject: [PATCH v4 25/25] rm/tilcdc: Add support for
 DRM_BRIDGE_ATTACH_NO_CONNECTOR

Convert the driver to use the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag when
attaching bridges. This modernizes the driver by delegating connector
creation to the bridge subsystem through drm_bridge_connector_init()
instead of manually searching for connectors created by the bridge.

The custom tilcdc_encoder_find_connector() function is removed and
replaced with the standard drm_bridge_connector infrastructure, which
simplifies the code and aligns with current DRM bridge best practices.

This change is safe as there are now no in-tree devicetrees that
connect tilcdc to bridges which do not support the
DRM_BRIDGE_ATTACH_NO_CONNECTOR flag.

Signed-off-by: Kory Maincent (TI.com) <kory.maincent@...tlin.com>
---

Changes in v4:
- Select missing DRM_BRIDGE_CONNECTOR and DRM_DISPLAY_HELPER config
  dependency in Kconfig
---
 drivers/gpu/drm/tilcdc/Kconfig          |  2 ++
 drivers/gpu/drm/tilcdc/tilcdc_encoder.c | 37 ++++++++++++++-------------------
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/tilcdc/Kconfig b/drivers/gpu/drm/tilcdc/Kconfig
index a36e809f984cd..80f53bdd0ace0 100644
--- a/drivers/gpu/drm/tilcdc/Kconfig
+++ b/drivers/gpu/drm/tilcdc/Kconfig
@@ -6,9 +6,11 @@ config DRM_TILCDC
 	select DRM_KMS_HELPER
 	select DRM_GEM_DMA_HELPER
 	select DRM_BRIDGE
+	select DRM_BRIDGE_CONNECTOR
 	select DRM_PANEL_BRIDGE
 	select VIDEOMODE_HELPERS
 	select BACKLIGHT_CLASS_DEVICE
+	select DRM_DISPLAY_HELPER
 	help
 	  Choose this option if you have an TI SoC with LCDC display
 	  controller, for example AM33xx in beagle-bone, DA8xx, or
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_encoder.c b/drivers/gpu/drm/tilcdc/tilcdc_encoder.c
index 546fe7e6ee815..680a2ac6ab594 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_encoder.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_encoder.c
@@ -8,45 +8,40 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
+#include <drm/drm_bridge_connector.h>
 #include <drm/drm_of.h>
 #include <drm/drm_simple_kms_helper.h>
 
 #include "tilcdc_drv.h"
 #include "tilcdc_encoder.h"
 
-static
-struct drm_connector *tilcdc_encoder_find_connector(struct drm_device *ddev,
-						    struct drm_encoder *encoder)
-{
-	struct drm_connector *connector;
-
-	list_for_each_entry(connector, &ddev->mode_config.connector_list, head) {
-		if (drm_connector_has_possible_encoder(connector, encoder))
-			return connector;
-	}
-
-	drm_err(ddev, "No connector found for %s encoder (id %d)\n",
-		encoder->name, encoder->base.id);
-
-	return NULL;
-}
-
 static
 int tilcdc_attach_bridge(struct drm_device *ddev, struct drm_bridge *bridge)
 {
 	struct tilcdc_drm_private *priv = ddev_to_tilcdc_priv(ddev);
+	struct drm_connector *connector;
 	int ret;
 
 	priv->encoder->base.possible_crtcs = BIT(0);
 
-	ret = drm_bridge_attach(&priv->encoder->base, bridge, NULL, 0);
+	ret = drm_bridge_attach(&priv->encoder->base, bridge, NULL,
+				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
 	if (ret)
 		return ret;
 
-	priv->connector = tilcdc_encoder_find_connector(ddev, &priv->encoder->base);
-	if (!priv->connector)
-		return -ENODEV;
+	connector = drm_bridge_connector_init(ddev, &priv->encoder->base);
+	if (IS_ERR(connector)) {
+		drm_err(ddev, "bridge_connector create failed\n");
+		return PTR_ERR(connector);
+	}
+
+	ret = drm_connector_attach_encoder(connector, &priv->encoder->base);
+	if (ret) {
+		drm_err(ddev, "attaching encoder to connector failed\n");
+		return ret;
+	}
 
+	priv->connector = connector;
 	return 0;
 }
 

-- 
2.43.0