drm/msm/mdp4: switch LVDS to use drm_bridge/_connector

LVDS support in MDP4 driver makes use of drm_connector directly. However
LCDC encoder and LVDS connector are wrappers around drm_panel. Switch
them to use drm_panel_bridge/drm_bridge_connector. This allows using
standard interface for the drm_panel and also inserting additional
bridges between encoder and panel.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/650290/
Link: https://lore.kernel.org/r/20250425-fd-mdp4-lvds-v4-6-6b212160b44c@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Author: lumag

drivers/gpu/drm/msm/Makefile

@@ -48,7 +48,6 @@ msm-display-$(CONFIG_DRM_MSM_MDP4) += \
 	disp/mdp4/mdp4_dsi_encoder.o \
 	disp/mdp4/mdp4_dtv_encoder.o \
 	disp/mdp4/mdp4_lcdc_encoder.o \
-	disp/mdp4/mdp4_lvds_connector.o \
 	disp/mdp4/mdp4_lvds_pll.o \
 	disp/mdp4/mdp4_irq.o \
 	disp/mdp4/mdp4_kms.o \

drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c

@@ -6,6 +6,8 @@
 
 #include <linux/delay.h>
 
+#include <drm/drm_bridge.h>
+#include <drm/drm_bridge_connector.h>
 #include <drm/drm_vblank.h>
 
 #include "msm_drv.h"
@@ -189,7 +191,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
 	struct msm_drm_private *priv = dev->dev_private;
 	struct drm_encoder *encoder;
 	struct drm_connector *connector;
-	struct device_node *panel_node;
+	struct drm_bridge *next_bridge;
 	int dsi_id;
 	int ret;
 
@@ -199,27 +201,43 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
 		 * bail out early if there is no panel node (no need to
 		 * initialize LCDC encoder and LVDS connector)
 		 */
-		panel_node = of_graph_get_remote_node(dev->dev->of_node, 0, 0);
-		if (!panel_node)
-			return 0;
+		next_bridge = devm_drm_of_get_bridge(dev->dev, dev->dev->of_node, 0, 0);
+		if (IS_ERR(next_bridge)) {
+			ret = PTR_ERR(next_bridge);
+			if (ret == -ENODEV)
+				return 0;
+			return ret;
+		}
 
-		encoder = mdp4_lcdc_encoder_init(dev, panel_node);
+		encoder = mdp4_lcdc_encoder_init(dev);
 		if (IS_ERR(encoder)) {
 			DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
-			of_node_put(panel_node);
 			return PTR_ERR(encoder);
 		}
 
 		/* LCDC can be hooked to DMA_P (TODO: Add DMA_S later?) */
 		encoder->possible_crtcs = 1 << DMA_P;
 
-		connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
+		ret = drm_bridge_attach(encoder, next_bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+		if (ret) {
+			DRM_DEV_ERROR(dev->dev, "failed to attach LVDS panel/bridge: %d\n", ret);
+
+			return ret;
+		}
+
+		connector = drm_bridge_connector_init(dev, encoder);
 		if (IS_ERR(connector)) {
 			DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
-			of_node_put(panel_node);
 			return PTR_ERR(connector);
 		}
 
+		ret = drm_connector_attach_encoder(connector, encoder);
+		if (ret) {
+			DRM_DEV_ERROR(dev->dev, "failed to attach LVDS connector: %d\n", ret);
+
+			return ret;
+		}
+
 		break;
 	case DRM_MODE_ENCODER_TMDS:
 		encoder = mdp4_dtv_encoder_init(dev);

drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.h

@@ -191,11 +191,7 @@ struct drm_crtc *mdp4_crtc_init(struct drm_device *dev,
 long mdp4_dtv_round_pixclk(struct drm_encoder *encoder, unsigned long rate);
 struct drm_encoder *mdp4_dtv_encoder_init(struct drm_device *dev);
 
-struct drm_encoder *mdp4_lcdc_encoder_init(struct drm_device *dev,
-		struct device_node *panel_node);
-
-struct drm_connector *mdp4_lvds_connector_init(struct drm_device *dev,
-		struct device_node *panel_node, struct drm_encoder *encoder);
+struct drm_encoder *mdp4_lcdc_encoder_init(struct drm_device *dev);
 
 #ifdef CONFIG_DRM_MSM_DSI
 struct drm_encoder *mdp4_dsi_encoder_init(struct drm_device *dev);

drivers/gpu/drm/msm/disp/mdp4/mdp4_lcdc_encoder.c

@@ -14,7 +14,6 @@
 
 struct mdp4_lcdc_encoder {
 	struct drm_encoder base;
-	struct device_node *panel_node;
 	struct drm_panel *panel;
 	struct clk *lcdc_clk;
 	unsigned long int pixclock;
@@ -262,19 +261,12 @@ static void mdp4_lcdc_encoder_disable(struct drm_encoder *encoder)
 	struct mdp4_lcdc_encoder *mdp4_lcdc_encoder =
 			to_mdp4_lcdc_encoder(encoder);
 	struct mdp4_kms *mdp4_kms = get_kms(encoder);
-	struct drm_panel *panel;
 
 	if (WARN_ON(!mdp4_lcdc_encoder->enabled))
 		return;
 
 	mdp4_write(mdp4_kms, REG_MDP4_LCDC_ENABLE, 0);
 
-	panel = of_drm_find_panel(mdp4_lcdc_encoder->panel_node);
-	if (!IS_ERR(panel)) {
-		drm_panel_disable(panel);
-		drm_panel_unprepare(panel);
-	}
-
 	/*
 	 * Wait for a vsync so we know the ENABLE=0 latched before
 	 * the (connector) source of the vsync's gets disabled,
@@ -300,7 +292,6 @@ static void mdp4_lcdc_encoder_enable(struct drm_encoder *encoder)
 			to_mdp4_lcdc_encoder(encoder);
 	unsigned long pc = mdp4_lcdc_encoder->pixclock;
 	struct mdp4_kms *mdp4_kms = get_kms(encoder);
-	struct drm_panel *panel;
 	uint32_t config;
 	int ret;
 
@@ -335,12 +326,6 @@ static void mdp4_lcdc_encoder_enable(struct drm_encoder *encoder)
 	if (ret)
 		DRM_DEV_ERROR(dev->dev, "failed to enable lcdc_clk: %d\n", ret);
 
-	panel = of_drm_find_panel(mdp4_lcdc_encoder->panel_node);
-	if (!IS_ERR(panel)) {
-		drm_panel_prepare(panel);
-		drm_panel_enable(panel);
-	}
-
 	setup_phy(encoder);
 
 	mdp4_write(mdp4_kms, REG_MDP4_LCDC_ENABLE, 1);
@@ -375,8 +360,7 @@ static const struct drm_encoder_helper_funcs mdp4_lcdc_encoder_helper_funcs = {
 };
 
 /* initialize encoder */
-struct drm_encoder *mdp4_lcdc_encoder_init(struct drm_device *dev,
-		struct device_node *panel_node)
+struct drm_encoder *mdp4_lcdc_encoder_init(struct drm_device *dev)
 {
 	struct drm_encoder *encoder;
 	struct mdp4_lcdc_encoder *mdp4_lcdc_encoder;
@@ -387,8 +371,6 @@ struct drm_encoder *mdp4_lcdc_encoder_init(struct drm_device *dev,
 	if (IS_ERR(mdp4_lcdc_encoder))
 		return ERR_CAST(mdp4_lcdc_encoder);
 
-	mdp4_lcdc_encoder->panel_node = panel_node;
-
 	encoder = &mdp4_lcdc_encoder->base;
 
 	drm_encoder_helper_add(encoder, &mdp4_lcdc_encoder_helper_funcs);