drm: lcdif: Check consistent bus format and flags across first bridges

The single LCDIF embedded in i.MX93 SoC may drive multiple displays
simultaneously.  Check bus format and flags across first bridges in
->atomic_check() to ensure they are consistent.  This is a preparation
for adding i.MX93 LCDIF support.
Acked-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510092450.4024730-5-victor.liu@nxp.com

drivers/gpu/drm/mxsfb/lcdif_drv.c

@@ -52,8 +52,6 @@ static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
 	if (ret)
 		return dev_err_probe(drm->dev, ret, "Failed to attach bridge\n");
 
-	lcdif->bridge = bridge;
-
 	return 0;
 }
 

drivers/gpu/drm/mxsfb/lcdif_drv.h

@@ -31,7 +31,6 @@ struct lcdif_drm_private {
 	} planes;
 	struct drm_crtc			crtc;
 	struct drm_encoder		encoder;
-	struct drm_bridge		*bridge;
 };
 
 static inline struct lcdif_drm_private *

drivers/gpu/drm/mxsfb/lcdif_kms.c

@@ -17,6 +17,7 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_color_mgmt.h>
+#include <drm/drm_connector.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_fb_dma_helper.h>
@@ -424,15 +425,19 @@ static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
 				   struct drm_atomic_state *state)
 {
 	struct drm_device *drm = crtc->dev;
-	struct lcdif_drm_private *lcdif = to_lcdif_drm_private(drm);
 	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state,
 									  crtc);
 	struct lcdif_crtc_state *lcdif_crtc_state = to_lcdif_crtc_state(crtc_state);
 	bool has_primary = crtc_state->plane_mask &
 			   drm_plane_mask(crtc->primary);
+	struct drm_connector_state *connector_state;
+	struct drm_connector *connector;
+	struct drm_encoder *encoder;
 	struct drm_bridge_state *bridge_state;
-	struct drm_bridge *bridge = lcdif->bridge;
-	int ret;
+	struct drm_bridge *bridge;
+	u32 bus_format, bus_flags;
+	bool format_set = false, flags_set = false;
+	int ret, i;
 
 	/* The primary plane has to be enabled when the CRTC is active. */
 	if (crtc_state->active && !has_primary)
@@ -442,29 +447,58 @@ static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
 	if (ret)
 		return ret;
 
-	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
-	if (!bridge_state)
-		lcdif_crtc_state->bus_format = MEDIA_BUS_FMT_FIXED;
-	else
-		lcdif_crtc_state->bus_format = bridge_state->input_bus_cfg.format;
-
-	if (lcdif_crtc_state->bus_format == MEDIA_BUS_FMT_FIXED) {
-		dev_warn_once(drm->dev,
-			      "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
-			      "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
-		lcdif_crtc_state->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
-	} else if (!lcdif_crtc_state->bus_format) {
-		/* If all else fails, default to RGB888_1X24 */
-		lcdif_crtc_state->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+	/* Try to find consistent bus format and flags across first bridges. */
+	for_each_new_connector_in_state(state, connector, connector_state, i) {
+		if (!connector_state->crtc)
+			continue;
+
+		encoder = connector_state->best_encoder;
+
+		bridge = drm_bridge_chain_get_first_bridge(encoder);
+		if (!bridge)
+			continue;
+
+		bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
+		if (!bridge_state)
+			bus_format = MEDIA_BUS_FMT_FIXED;
+		else
+			bus_format = bridge_state->input_bus_cfg.format;
+
+		if (bus_format == MEDIA_BUS_FMT_FIXED) {
+			dev_warn(drm->dev,
+				 "[ENCODER:%d:%s]'s bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
+				 "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n",
+				 encoder->base.id, encoder->name);
+			bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+		} else if (!bus_format) {
+			/* If all else fails, default to RGB888_1X24 */
+			bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+		}
+
+		if (!format_set) {
+			lcdif_crtc_state->bus_format = bus_format;
+			format_set = true;
+		} else if (lcdif_crtc_state->bus_format != bus_format) {
+			DRM_DEV_DEBUG_DRIVER(drm->dev, "inconsistent bus format\n");
+			return -EINVAL;
+		}
+
+		if (bridge->timings)
+			bus_flags = bridge->timings->input_bus_flags;
+		else if (bridge_state)
+			bus_flags = bridge_state->input_bus_cfg.flags;
+		else
+			bus_flags = 0;
+
+		if (!flags_set) {
+			lcdif_crtc_state->bus_flags = bus_flags;
+			flags_set = true;
+		} else if (lcdif_crtc_state->bus_flags != bus_flags) {
+			DRM_DEV_DEBUG_DRIVER(drm->dev, "inconsistent bus flags\n");
+			return -EINVAL;
+		}
 	}
 
-	if (bridge->timings)
-		lcdif_crtc_state->bus_flags = bridge->timings->input_bus_flags;
-	else if (bridge_state)
-		lcdif_crtc_state->bus_flags = bridge_state->input_bus_cfg.flags;
-	else
-		lcdif_crtc_state->bus_flags = 0;
-
 	return 0;
 }