drm/qxl: fix framebuffer dirty rectangle tracking.

Commit "c0fe07a drm/qxl: rewrite framebuffer support" has a bug in the
dirty rectangle tracking:  Instead of ignoring an empty dirty rectangle
when adding a new dirty region the dirty region gets extended to the
upper left corner.  Fix it.

Cc: linux-stable@vger.kernel.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/qxl/qxl_fb.c b/drivers/gpu/drm/qxl/qxl_fb.c
index 41c422f..c4a5526 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_fb.c
+++ b/drivers/gpu/drm/qxl/qxl_fb.c
@@ -144,14 +144,17 @@ static void qxl_dirty_update(struct qxl_fbdev *qfbdev,
 
        spin_lock_irqsave(&qfbdev->dirty.lock, flags);
 
-       if (qfbdev->dirty.y1 < y)
-               y = qfbdev->dirty.y1;
-       if (qfbdev->dirty.y2 > y2)
-               y2 = qfbdev->dirty.y2;
-       if (qfbdev->dirty.x1 < x)
-               x = qfbdev->dirty.x1;
-       if (qfbdev->dirty.x2 > x2)
-               x2 = qfbdev->dirty.x2;
+       if ((qfbdev->dirty.y2 - qfbdev->dirty.y1) &&
+           (qfbdev->dirty.x2 - qfbdev->dirty.x1)) {
+               if (qfbdev->dirty.y1 < y)
+                       y = qfbdev->dirty.y1;
+               if (qfbdev->dirty.y2 > y2)
+                       y2 = qfbdev->dirty.y2;
+               if (qfbdev->dirty.x1 < x)
+                       x = qfbdev->dirty.x1;
+               if (qfbdev->dirty.x2 > x2)
+                       x2 = qfbdev->dirty.x2;
+       }
 
        qfbdev->dirty.x1 = x;
        qfbdev->dirty.x2 = x2;