sna: Fix attaching to a headless configuration

ADDFB fails with a headless config (as any fb size is invalid).
Fortunately, with headless we can use any depth we like.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/sna/sna_driver.c b/src/sna/sna_driver.c
index 4b35fe96..66f72dc2 100644
--- a/src/sna/sna_driver.c
+++ b/src/sna/sna_driver.c
@@ -445,8 +445,14 @@ static Bool fb_supports_depth(int fd, int depth)
 {
 	struct drm_i915_gem_create create;
 	struct drm_mode_fb_cmd fb;
+	struct drm_mode_card_res res;
 	Bool ret;
 
+	memset(&res, 0, sizeof(res));
+	(void)drmIoctl(fd, DRM_IOCTL_MODE_GETRESOURCES, &res);
+	if (res.count_crtcs == 0)
+		return TRUE;
+
 	VG_CLEAR(create);
 	create.handle = 0;
 	create.size = 4096;