From 7c55c51408e55f08bfb4ee6930879310030da97e Mon Sep 17 00:00:00 2001
From: Christoph Haag <christoph.haag@collabora.com>
Date: Fri, 4 Mar 2022 16:00:49 +0100
Subject: [PATCH] st/gui: Add warning when v4l driver is disabled on linux

"Failed to open camera!" is a very uninformative error
---
 src/xrt/state_trackers/gui/gui_scene_video.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/xrt/state_trackers/gui/gui_scene_video.c b/src/xrt/state_trackers/gui/gui_scene_video.c
index eaf3d0e56..8e0eb489a 100644
--- a/src/xrt/state_trackers/gui/gui_scene_video.c
+++ b/src/xrt/state_trackers/gui/gui_scene_video.c
@@ -11,6 +11,7 @@
 #include "xrt/xrt_settings.h"
 #include "xrt/xrt_frameserver.h"
 #include "xrt/xrt_config_drivers.h"
+#include "xrt/xrt_config_os.h"
 
 #include "util/u_misc.h"
 #include "util/u_format.h"
@@ -115,6 +116,9 @@ on_video_device(struct xrt_prober *xp,
 	xrt_prober_open_video_device(xp, pdev, vs->xfctx, &vs->xfs);
 	if (vs->xfs == NULL) {
 		U_LOG_E("Failed to open camera!");
+#if defined(XRT_OS_LINUX) && !defined(XRT_HAVE_V4L2)
+		U_LOG_E("Monado was built with the v4l driver disabled. Most video devices require this driver!");
+#endif
 		free(vs->xfctx);
 		vs->xfctx = NULL;
 		return;