drm/vc4: Don't try to initialize FBDEV if we're only bound to V3D.

There's no sense in having an fbdev if there's no display, since
connectors don't get hotplugged to this hardware.  On Cygnus we were
getting a dmesg error from passing in num_connectors (0), when that
argument is supposed to be the maximum number of cloned connectors per
CRTC (1).

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170428224223.21904-2-eric@anholt.net

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index ad7925a9e0ea..237a504f11f0 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -230,10 +230,12 @@ int vc4_kms_load(struct drm_device *dev)
 
         drm_mode_config_reset(dev);
 
-        vc4->fbdev = drm_fbdev_cma_init(dev, 32,
-                                        dev->mode_config.num_connector);
-        if (IS_ERR(vc4->fbdev))
-                vc4->fbdev = NULL;
+        if (dev->mode_config.num_connector) {
+                vc4->fbdev = drm_fbdev_cma_init(dev, 32,
+                                                dev->mode_config.num_connector);
+                if (IS_ERR(vc4->fbdev))
+                        vc4->fbdev = NULL;
+        }
 
         drm_kms_helper_poll_init(dev);