From: Boris Brezillon <boris.brezillon@bootlin.com>
Date: Wed, 9 May 2018 15:00:42 +0200
Subject: drm/vc4: Support the case where the DSI device is disabled
Git-commit: 1b9883eae82251b742627ebd9d544d1b1bddf121
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Having a device with a status property != "okay" in the DT is a valid
use case, and we should not prevent the registration of the DRM device
when the DSI device connected to the DSI controller is disabled.

Consider the ENODEV return code as a valid result and do not expose the
DSI encoder/connector when it happens.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180509130042.9435-5-boris.brezillon@bootlin.com

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/vc4/vc4_dsi.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -1612,8 +1612,18 @@ static int vc4_dsi_bind(struct device *d
 
 	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
 					  &panel, &dsi->bridge);
-	if (ret)
+	if (ret) {
+		/* If the bridge or panel pointed by dev->of_node is not
+		 * enabled, just return 0 here so that we don't prevent the DRM
+		 * dev from being registered. Of course that means the DSI
+		 * encoder won't be exposed, but that's not a problem since
+		 * nothing is connected to it.
+		 */
+		if (ret == -ENODEV)
+			return 0;
+
 		return ret;
+	}
 
 	if (panel) {
 		dsi->bridge = devm_drm_panel_bridge_add(dev, panel,
@@ -1664,7 +1674,8 @@ static void vc4_dsi_unbind(struct device
 	struct vc4_dev *vc4 = to_vc4_dev(drm);
 	struct vc4_dsi *dsi = dev_get_drvdata(dev);
 
-	pm_runtime_disable(dev);
+	if (dsi->bridge)
+		pm_runtime_disable(dev);
 
 	vc4_dsi_encoder_destroy(dsi->encoder);