drm/amdgpu: keep fbdev buffers pinned during suspend

Was dropped when we converted to the generic helpers.

Fixes: 087451f3 ("drm/amdgpu: use generic fb helpers instead of setting up AMD own's.")
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_display.c

@@ -1528,6 +1528,21 @@ bool amdgpu_crtc_get_scanout_position(struct drm_crtc *crtc,
 						  stime, etime, mode);
 }
 
+static bool
+amdgpu_display_robj_is_fb(struct amdgpu_device *adev, struct amdgpu_bo *robj)
+{
+	struct drm_device *dev = adev_to_drm(adev);
+	struct drm_fb_helper *fb_helper = dev->fb_helper;
+
+	if (!fb_helper || !fb_helper->buffer)
+		return false;
+
+	if (gem_to_amdgpu_bo(fb_helper->buffer->gem) != robj)
+		return false;
+
+	return true;
+}
+
 int amdgpu_display_suspend_helper(struct amdgpu_device *adev)
 {
 	struct drm_device *dev = adev_to_drm(adev);
@@ -1563,10 +1578,12 @@ int amdgpu_display_suspend_helper(struct amdgpu_device *adev)
 			continue;
 		}
 		robj = gem_to_amdgpu_bo(fb->obj[0]);
-		r = amdgpu_bo_reserve(robj, true);
-		if (r == 0) {
-			amdgpu_bo_unpin(robj);
-			amdgpu_bo_unreserve(robj);
+		if (!amdgpu_display_robj_is_fb(adev, robj)) {
+			r = amdgpu_bo_reserve(robj, true);
+			if (r == 0) {
+				amdgpu_bo_unpin(robj);
+				amdgpu_bo_unreserve(robj);
+			}
 		}
 	}
 	return 0;