drm/bridge: sn65dsi86: defer if there is no dsi host

Otherwise we don't get another shot at it if the bridge probes before
the dsi host is registered.  It seems like this is what *most* (but not
all) of the other bridges do.

It looks like this was missed in the conversion to attach dsi host at
probe time.

Fixes: c3b75d47 ("drm/bridge: sn65dsi86: Register and attach our DSI device at probe")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
[dianders: squashed in Stephen's simplification]
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211207215753.635841-1-robdclark@gmail.com

drivers/gpu/drm/bridge/ti-sn65dsi86.c

@@ -704,7 +704,7 @@ static struct ti_sn65dsi86 *bridge_to_ti_sn65dsi86(struct drm_bridge *bridge)
 
 static int ti_sn_attach_host(struct ti_sn65dsi86 *pdata)
 {
-	int ret, val;
+	int val;
 	struct mipi_dsi_host *host;
 	struct mipi_dsi_device *dsi;
 	struct device *dev = pdata->dev;
@@ -714,16 +714,12 @@ static int ti_sn_attach_host(struct ti_sn65dsi86 *pdata)
 	};
 
 	host = of_find_mipi_dsi_host_by_node(pdata->host_node);
-	if (!host) {
-		DRM_ERROR("failed to find dsi host\n");
-		return -ENODEV;
-	}
+	if (!host)
+		return -EPROBE_DEFER;
 
 	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
-	if (IS_ERR(dsi)) {
-		DRM_ERROR("failed to create dsi device\n");
+	if (IS_ERR(dsi))
 		return PTR_ERR(dsi);
-	}
 
 	/* TODO: setting to 4 MIPI lanes always for now */
 	dsi->lanes = 4;
@@ -739,13 +735,7 @@ static int ti_sn_attach_host(struct ti_sn65dsi86 *pdata)
 
 	pdata->dsi = dsi;
 
-	ret = devm_mipi_dsi_attach(dev, dsi);
-	if (ret < 0) {
-		DRM_ERROR("failed to attach dsi to host\n");
-		return ret;
-	}
-
-	return 0;
+	return devm_mipi_dsi_attach(dev, dsi);
 }
 
 static int ti_sn_bridge_attach(struct drm_bridge *bridge,
@@ -1267,8 +1257,10 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
 	drm_bridge_add(&pdata->bridge);
 
 	ret = ti_sn_attach_host(pdata);
-	if (ret)
+	if (ret) {
+		dev_err_probe(pdata->dev, ret, "failed to attach dsi host\n");
 		goto err_remove_bridge;
+	}
 
 	return 0;