drm: exynos: dsi: Restore proper bridge chain order

Restore the proper bridge chain by finding the previous bridge
in the chain instead of passing NULL.

This establishes a proper bridge chain while attaching downstream
bridges.
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_dsi.c

@@ -1445,7 +1445,8 @@ static int exynos_dsi_attach(struct drm_bridge *bridge,
 {
 	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
 
-	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, NULL, flags);
+	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, bridge,
+				 flags);
 }
 
 static const struct drm_bridge_funcs exynos_dsi_bridge_funcs = {
@@ -1491,7 +1492,10 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
 
 	drm_bridge_add(&dsi->bridge);
 
-	drm_bridge_attach(encoder, &dsi->bridge, NULL, 0);
+	drm_bridge_attach(encoder, &dsi->bridge,
+			  list_first_entry_or_null(&encoder->bridge_chain,
+						   struct drm_bridge,
+						   chain_node), 0);
 
 	/*
 	 * This is a temporary solution and should be made by more generic way.
@@ -1726,6 +1730,7 @@ static int exynos_dsi_probe(struct platform_device *pdev)
 	dsi->bridge.funcs = &exynos_dsi_bridge_funcs;
 	dsi->bridge.of_node = dev->of_node;
 	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
+	dsi->bridge.pre_enable_prev_first = true;
 
 	ret = component_add(dev, &exynos_dsi_component_ops);
 	if (ret)