i915: Don't dereference HWS in /proc debug files when it isn't initialized.

Signed-off-by: Eric Anholt <[e-mail]>
Acked-by: Keith Packard <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/i915/i915_gem_proc.c

···
 
 	*start = &buf[offset];
 	*eof = 0;
-	DRM_PROC_PRINT("Current sequence: %d\n", i915_get_gem_seqno(dev));
+	if (dev_priv->hw_status_page != NULL) {
+		DRM_PROC_PRINT("Current sequence: %d\n",
+			       i915_get_gem_seqno(dev));
+	} else {
+		DRM_PROC_PRINT("Current sequence: hws uninitialized\n");
+	}
 	DRM_PROC_PRINT("Waiter sequence:  %d\n",
 		       dev_priv->mm.waiting_gem_seqno);
 	DRM_PROC_PRINT("IRQ sequence:     %d\n", dev_priv->mm.irq_gem_seqno);
···
 		       I915_READ(PIPEBSTAT));
 	DRM_PROC_PRINT("Interrupts received: %d\n",
 		       atomic_read(&dev_priv->irq_received));
-	DRM_PROC_PRINT("Current sequence:    %d\n",
-		       i915_get_gem_seqno(dev));
+	if (dev_priv->hw_status_page != NULL) {
+		DRM_PROC_PRINT("Current sequence:    %d\n",
+			       i915_get_gem_seqno(dev));
+	} else {
+		DRM_PROC_PRINT("Current sequence:    hws uninitialized\n");
+	}
 	DRM_PROC_PRINT("Waiter sequence:     %d\n",
 		       dev_priv->mm.waiting_gem_seqno);
 	DRM_PROC_PRINT("IRQ sequence:        %d\n",