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

Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i915/i915_gem_proc.c

@@ -192,7 +192,12 @@ static int i915_gem_seqno_info(char *buf, char **start, off_t offset,
 
 	*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);
@@ -230,8 +235,12 @@ static int i915_interrupt_info(char *buf, char **start, off_t offset,
 		       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",