drm/i915: Fix updating FBC

We need to track different state on each generation in order to detect
when we need to refresh the FBC registers.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -719,6 +719,9 @@ static int i915_fbc_status(struct seq_file *m, void *unused)
 	} else {
 		seq_printf(m, "FBC disabled: ");
 		switch (dev_priv->no_fbc_reason) {
+		case FBC_NO_OUTPUT:
+			seq_printf(m, "no outputs");
+			break;
 		case FBC_STOLEN_TOO_SMALL:
 			seq_printf(m, "not enough stolen memory");
 			break;

drivers/gpu/drm/i915/i915_drv.h

@@ -219,6 +219,7 @@ struct intel_device_info {
 };
 
 enum no_fbc_reason {
+	FBC_NO_OUTPUT, /* no outputs enabled to compress */
 	FBC_STOLEN_TOO_SMALL, /* not enough space to hold compressed buffers */
 	FBC_UNSUPPORTED_MODE, /* interlace or doublescanned mode */
 	FBC_MODE_TOO_LARGE, /* mode too large for compression */
@@ -307,8 +308,10 @@ typedef struct drm_i915_private {
 
 	unsigned long cfb_size;
 	unsigned long cfb_pitch;
+	unsigned long cfb_offset;
 	int cfb_fence;
 	int cfb_plane;
+	int cfb_y;
 
 	int irq_enabled;