drm/i915: Squelch repeated reasoning for why FBC cannot be activated

Almost invariably the reason why FBC cannot be turned on is the same
every time (disabled via parameter, too many pipes, pipe too large etc)
as modesetting and framebuffer configuration changes less frequently
than trying to enable FBC.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index ed72fe0..eed2f4c 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1099,6 +1099,12 @@
 	} else {
 		seq_puts(m, "FBC disabled: ");
 		switch (dev_priv->fbc.no_fbc_reason) {
+		case FBC_OK:
+			seq_puts(m, "FBC actived, but currently disabled in hardware");
+			break;
+		case FBC_UNSUPPORTED:
+			seq_puts(m, "unsupported by this chipset");
+			break;
 		case FBC_NO_OUTPUT:
 			seq_puts(m, "no outputs");
 			break;