drm/i915/execlists: Use rmb() to order CSB reads

[linux-2.6-microblaze.git] / drivers / gpu / drm / i915 / intel_lrc.c

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index e3a5f67..8704f7f 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -884,6 +884,7 @@ static void execlists_submission_tasklet(unsigned long data)
 
                        head = execlists->csb_head;
                        tail = READ_ONCE(buf[write_idx]);
+                       rmb(); /* Hopefully paired with a wmb() in HW */
                }
                GEM_TRACE("%s cs-irq head=%d [%d%s], tail=%d [%d%s]\n",
                          engine->name,