drm/imx: ldb: drop custom DDC bus support

None of the boards ever supported by the upstream kernel used the custom
DDC bus support with the LDB connector. If a need arises to do so, one
should use panel-simple and its DDC bus code. Drop ddc-i2c-bus support
from the imx-ldb driver.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Chris Healy <cphealy@gmail.com>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de> # on imx6q-nitrogen6x
Link: https://patchwork.freedesktop.org/patch/msgid/20240602-drm-imx-cleanup-v3-6-e549e2a43100@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/imx/ipuv3/imx-ldb.c

@@ -25,7 +25,6 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
-#include <drm/drm_edid.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
@@ -70,7 +69,6 @@ struct imx_ldb_channel {
 	struct drm_bridge *bridge;
 
 	struct device_node *child;
-	struct i2c_adapter *ddc;
 	int chno;
 	struct drm_display_mode mode;
 	int mode_valid;
@@ -141,18 +139,6 @@ static int imx_ldb_connector_get_modes(struct drm_connector *connector)
 	if (num_modes > 0)
 		return num_modes;
 
-	if (imx_ldb_ch->ddc) {
-		const struct drm_edid *edid = drm_edid_read_ddc(connector,
-								imx_ldb_ch->ddc);
-
-		if (edid) {
-			drm_edid_connector_update(connector, edid);
-			drm_edid_free(edid);
-
-			return drm_edid_connector_add_modes(connector);
-		}
-	}
-
 	if (imx_ldb_ch->mode_valid) {
 		struct drm_display_mode *mode;
 
@@ -481,10 +467,9 @@ static int imx_ldb_register(struct drm_device *drm,
 		 */
 		drm_connector_helper_add(connector,
 					 &imx_ldb_connector_helper_funcs);
-		drm_connector_init_with_ddc(drm, connector,
+		drm_connector_init(drm, connector,
-					    &imx_ldb_connector_funcs,
+				   &imx_ldb_connector_funcs,
-					    DRM_MODE_CONNECTOR_LVDS,
+				   DRM_MODE_CONNECTOR_LVDS);
-					    imx_ldb_ch->ddc);
 		drm_connector_attach_encoder(connector, encoder);
 	}
 
@@ -551,39 +536,6 @@ static const struct of_device_id imx_ldb_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, imx_ldb_dt_ids);
 
-static int imx_ldb_panel_ddc(struct device *dev,
-		struct imx_ldb_channel *channel, struct device_node *child)
-{
-	struct device_node *ddc_node;
-	int ret;
-
-	ddc_node = of_parse_phandle(child, "ddc-i2c-bus", 0);
-	if (ddc_node) {
-		channel->ddc = of_find_i2c_adapter_by_node(ddc_node);
-		of_node_put(ddc_node);
-		if (!channel->ddc) {
-			dev_warn(dev, "failed to get ddc i2c adapter\n");
-			return -EPROBE_DEFER;
-		}
-	}
-
-	if (!channel->ddc) {
-		/* if no DDC available, fallback to hardcoded EDID */
-		dev_dbg(dev, "no ddc available\n");
-
-		if (!channel->panel) {
-			/* fallback to display-timings node */
-			ret = of_get_drm_display_mode(child,
-						      &channel->mode,
-						      &channel->bus_flags,
-						      OF_USE_NATIVE_MODE);
-			if (!ret)
-				channel->mode_valid = 1;
-		}
-	}
-	return 0;
-}
-
 static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
 {
 	struct drm_device *drm = data;
@@ -694,11 +646,15 @@ static int imx_ldb_probe(struct platform_device *pdev)
 		if (ret && ret != -ENODEV)
 			goto free_child;
 
-		/* panel ddc only if there is no bridge */
+		if (!channel->bridge && !channel->panel) {
-		if (!channel->bridge) {
+			ret = of_get_drm_display_mode(child,
-			ret = imx_ldb_panel_ddc(dev, channel, child);
+						      &channel->mode,
+						      &channel->bus_flags,
+						      OF_USE_NATIVE_MODE);
 			if (ret)
 				goto free_child;
+
+			channel->mode_valid = 1;
 		}
 
 		bus_format = of_get_bus_format(dev, child);
@@ -732,15 +688,6 @@ free_child:
 
 static void imx_ldb_remove(struct platform_device *pdev)
 {
-	struct imx_ldb *imx_ldb = platform_get_drvdata(pdev);
-	int i;
-
-	for (i = 0; i < 2; i++) {
-		struct imx_ldb_channel *channel = &imx_ldb->channel[i];
-
-		i2c_put_adapter(channel->ddc);
-	}
-
 	component_del(&pdev->dev, &imx_ldb_ops);
 }