modesetting: resubmit dirty rects on EINVAL (v2)

This error code can mean we're submitting more rects at once than the
driver can handle. If that happens, resubmit one at a time.

v2: Make the rect submit loop more error-proof (Walter Harms)

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Michael Thayer <michael.thayer@oracle.com>

hw/xfree86/drivers/modesetting/driver.c

@@ -515,6 +515,15 @@ dispatch_dirty_region(ScrnInfoPtr scrn,
 
         /* TODO query connector property to see if this is needed */
         ret = drmModeDirtyFB(ms->fd, fb_id, clip, num_cliprects);
+
+        /* if we're swamping it with work, try one at a time */
+        if (ret == -EINVAL) {
+            for (i = 0; i < num_cliprects; i++) {
+                if ((ret = drmModeDirtyFB(ms->fd, fb_id, &clip[i], 1)) < 0)
+                    break;
+            }
+        }
+
         free(clip);
         DamageEmpty(damage);
     }